I'm looking to upgrade the factory Colt 6721 mil-spec trigger.  My AR is my primary defense weapon, sitting beneath my desk at work and next to my bed at home.  However, I also take it to the range at least weekly.  So, I'd like a trigger appropriate for both uses.  I called Geissele today and they recommended the SSA, but I am open to other recommendations.

I can't speak from personal experience, but I hear nothing but great things about Gieselle SSA trigger.  I have one coming in soon and can't wait to try it.

Geissele all of the things. SOPMOD certified as well. I have 7 and they are good to go.

I have a number of rifles with LaRue MBT triggers in them.  I actually prefer them to the Gieselle triggers.

No experience with Geissele, but I really like my MBT, especially since it was $99 on sale. Heck of a trigger for the money.

Do you want a single stage or 2 stage trigger ? Single stage Hiperfire 24 3G is the one you want. 2 Stage Gessielle SSA. I personally like single stage triggers but its all about personal preference

POF 3.5 Straight Trigger is a good one for the money. I saw a couple used for 75-80$ on the EE.

ALG ACT is a good "mil spec" AR trigger.  I got one used for 30$.

Geissele SSA is my favorite, but its 200$+

The larue trigger with the i can wait option is a good deal. I'd recommend it as well.

The LaRue MBT is great and much cheaper.

Hiperfire Enhanced Duty Trigger, user-adjustable trigger pull of 4.5 or 5.5lbs while still maintaining full hammer strike energy for $85: https://www.aimsurplus.com/product.aspx?item=XHTEDT&name=HIPERFIRE+HIPERTOUCH+EDT+Performance+AR+Trigger&groupid=2357
Tried one on the recommendation of a fellow ARFCOMmer and now all my AR's have EDT's (as well as several friends and family members who purchased one after trying one of mine).

Tomac

knowing if you like a single stage vs a 2 stage trigger is a big step to deciding what you want to go with.  Trying before you buy is the best way to get a feel for what trigger you like the best.  I wouldn't rule one specific trigger out, unless you try it yourself.  It really comes down to user preference.  

AR Gold
Geissele S3G, SD3G
Geissele SSA
Geissele G2S
Hiperfire 24 3G
RRA National Match 2 stage trigger
MBT
Elf

All of these are great triggers and you would be fine using any of them.  I like the AR gold trigger as my go to trigger, predictable break.  Also a fan of the S3G trigger when I just want to shoot fast - not as much for 300-500 yard shots.

Rise Armament RA-140 or even the RA-535. Both are very nice!

Velocity single stage is really nice if you prefer single stage.  They have 3.5 and 4.5 LB options.  4.5lb would be good for your defense use.  Not to light, but way better than milspec.  Check out the truth about guns website.  They have a comparison with computerized results comparing a decent amount of single stage triggers

It seems the Geissele SSA is the recommendation from most as well as my gunsmith.  I'm debating now on the regular or the SSA-E, which has a lighter pull.  While this is a defense gun meaning it sits under my desk at work and next to my bed at home, I take it to the range weekly at least, so I'd like something competition level.

I think the SSA will be your best compromise choice.  My precision recce has a 3.5 pound total pull through SSA-E.  It is incredible, especially the very crisp 1.2 lb. second stage.  With that barrel and trigger sub MOA is the norm with good match ammo and 1/2 MOA with benchrest quality handloaded components and doing my part.

But, I consider it a bit light for HD.  When I built my dedicated HD carbine I used an already well broken in smooth mil spec weight fire control group.  7 pounds.  When things go bump in the night and I am half asleep, maybe had a night cap or two, stress is high and adrenaline flowing, I don't want a negligent discharge.

The 4.5 pound SSA is great for a more general purpose build that includes HD.  If I had to do it all with one trigger, it would be SSA.  I think 4.5 lbs or so should be the safe minimum for high stress nighttime HD.

I have a Geissele SD-C and a CMC 4.5 lb flat bow trigger.
I'd highly recommend both

Geissele SSA or G2S ... both rock solid triggers and will be a hell of a lot better than mil spec

Three rifles, CMC Flat trigger in one, used with a scope.  Hiperfire 24-C in another with red dot.  And my HD rifle wears a Primary Arms Advanced Micro Dot left on 24/7 with an ALG-ACT Trigger.  Love all of them!

The ALG ACT, not Geissele SSA.  

The SSA is a fantastic trigger, no doubt about it.  But for a combat weapon, I would not go with that light a trigger.  The ACT is guaranteed to be "not less than 5.5 pounds" pull, meeting military standards.  It is extremely smooth, making it feel a lot lighter than a standard trigger.

This

I use the Geissele SSA trigger in all of my ARs. Get one, you won't regret it.

I have used several different two stage match triggers, and hands down the best one I have used is still a Rock River.  Crisp, no creep, strong reset. I have not used an MBT yet though.

The nice thing about the Geissele SSA and SSA-E is that the only difference is the spring weights, and you can order the springs separately from Geissele to convert one to the other.

I have a Rock River National Match Two Stage and a LaRue MBT. I'm not a "trigger connoisseur" but honestly when you compare the two side by side, they are very similar if not almost identical. The RRA is very crisp and a great value at @90$.
Legal Transfers (Industry Partner) has the RRA's for $88 shipped.

So I ended up getting the TriggerTech Adaptable AR Primary Trigger with the straight flat face option.  I like the look of the PVD option but I would have had to order direct from TriggerTech instead of Brownells, and I am impatient. The major decision to get this trigger was the ability to adjust it from 2.5-5 lbs total force very simply with a hex key.  So, at the range, I can dial it down, then tighten it up when using it for defense.  I am IN LOVE with the trigger.  Even my gunsmith, a die-hard Geissele fan, told me the is the crispest trigger he has ever felt and ordered one as soon as he finished installing mine.  I'm slowly gathering the equipment needed to do my own builds, and once I do I'm sure I am going to experiment with many triggers, including the acclaimed Geissele, but honestly I can't imagine anything being nicer than this.  This trigger removes the possibility of so many human errors affecting a shot (ex. pulling the gun to the right as you squeeze a heavy trigger).  I'm going to finish all of the customizations I want to do to this particular firearm, while watching over my gunsmith's shoulder, and then am attempting my own build.  He has installed for me an SLR very low profile gas block, Daniel Defense MFR 13.5" free floating rail, Daniel Defense rubberized grip and enlarged trigger guard, the TriggerTech trigger, and a Vortex Spitfire 3x, which I was planning on buying as a toy until I got an ACOG, but after having the range master bore sight it, it is so dead accurate and bright, I think I am just going to leave it on this rifle and get the ACOG for something else.  So, just wanted to sing the praises of this trigger.  I have never shot another aftermarket trigger, so I don't really have a basis of comparison, but between my gunsmith and a few other higher level enthusiasts, I can say objectively and subjectively that it is AMAZING!!!

Price?

Geissele is always the answer. SSA-E is my favorite all around trigger.

Geisseles are very, very nice. Guy at TT”AG said his took a dump on a suppressed SBR on a hard firing schedule, so they're not bullet proof. Still, a superior trigger with an excellent feel.

I took a chance on a HIPERTOUCH EDT.  It seems to be exceptionally robust. Really smacks the primers!  And there's something about the feel. Superb reset. There's just a touch of creep right before one of the lightest, crispest breaks I've ever experienced. At first this bit of creep annoyed me, and I thought about selling the trigger. But the more I shot it, the more I liked it. The tiny bit of creep let's me know that the break is near. Like a tiny, tactile safety wall. I've grown to really like it. Best match trigger I've ever owned, and I've owned a few. I tuned mine to about 2 1/2 pounds. Perfect.

ALG ACT, it has a nice trigger pull, but keeps the reliability and trigger weight of a standard trigger.

I think it comes with a 5.5lb and a 3.5 or 4 lb trigger. I have the 5.5, so if I do pull the trigger it's deliberate.

I never quite bought into the need for a heavier pull for safety. I mean, sure, a 1 pound trigger is scary, but... The deliberate part for me is simply exercising safety fundamentals -- finger off the trigger and safety left on at all times until the target is in the sights and the shot is a go. I was surprised to learn that even top tier spec ops guys flip their safeties on between fast shot strings in combat. Couldn't believe it.  In any case, I don't want to compromise accuracy for a margin of safety that can be handled at another level. A 2 1/2 - 3 pound pull is the sweet spot for me. But, to each their own. Triggers are one of those very, very subjective things about a man's weapon.

The standard minimum trigger pull for the M16/M4 family of weapons is 5.5 pounds.  There's a reason for this.  5.5 pounds isn't all that much, but as noted above, it takes a deliberate action to fire the weapon.  My SSA-E isn't exactly a "hair trigger," but it is possible to get all the way into the first stage before you realize it, and then you have a VERY light pull for the second stage...

To me, if you're even possibly going to be moving around with a weapon, an extra light trigger is a bad idea.  And I can just see whole herds of Bubbas who have bought the lightest triggers they can find having multiple negligent discharges the first time they start getting off the shooting bench at the range...

So my suggestion is still the ALG ACT, which feels almost as light as my SSA-E, but since it's a single stage trigger doesn't let me get too close to firing the rifle without meaning to.

No worries, friend. That's why the make different strokes for different folks. If you feel safer with that, that's what you should roll with. I'm just saying that the safety and the trigger guard are there for a reason. If one practices the fundamentals of safety religiously, there's no need to fear a lighter trigger.

Unless something dangerous is danger close, finger off the trigger. Same thing at the range until the target is in the scope. Safety on until the target is acquired and confirmed to be shootable.  Follow that, and only things that should be shot, will be shot.  If you don't follow that, a heavier trigger will provide only a very small margin of safety.

One can learn to manage a heavier trigger, but a lighter one generally improves accuracy.