I am building/purchasing my first AR in 2 parts. A comp DPMS BA-16TB upper and A STD ROCK RIVER lower. Now as you may ma not know the "Tuber" is completly shrouded in an aluminum tube giving it an appearance of being silenced. Now sice it has a flattop I was wondering what Optics choices I might have? What's everyone use and why? I can't afford the ACOG'S.
I have looked a the Eotech and can deal with the $300+ price tag. My local shop wasn't much help... telling me what do I like and how much do I want to spend. That was the extent of the conversaion.

I am building the same gun(I have the tuber but might not use it ,depends on the balance~if the barrel ever gets here)I planed on using a Eotech,but I am thinking OKO...I have several AR's each set up for diffrent stuff...this one will be a convertable from close quarter to bi-pod tack driver.....my sort of one gun...the OKO is a quality red dot..and the 110.00 I will save on it vs the Eotech will buy a quality detach scope mount, I think its a good trade off...a 30.00 BSA aint a option for me..

I have an EOTech on a 16" midweight flat top AR15 and I find it to be quicker and more precise than irons (no surprise there).

I also have a conventional scope (Leupold 4.5-14x) on a bull barrel flat-top for varmint/target work.  The scope is unbeatable for varmints out to 300 yards as you can locate and aim at things too small to see with the naked eye at distance. But you need to be rested (bi-pod, back pack, etc) to take advantage of the scoped rig.

Eye releif is non-critical with the EOTech, so you can mount it froward over the handguard if you like or on top of the upper, makes no difference.

Other AR's wear iron sights, but personally I find I can shoot 1/2 size groups with the EOTech as compared to same rifle with iron sights.

Hope this helps.

(edited to correct sp. errors)

Medic think about this a "16" barrel is  battle length it may be able to hit an object out to some distance , but is designed for distances similar to those of a handgun I would look no further than the Eotech - its reticle on target -bang target hit,there is no front sight or rear sight to allign or crosshair to adjust .Scopes are nice for all this varmint shooting 'they' do but a carbine is designed for close quarters and the more you can see with the naked eye the more likely you are to survive a situation that calls for a carbine .Go with the Eotech once you use it you will realize how cumbersome a scope is unless of course you dont make the same mistake I made by buying several scopes when I really wanted a Eotech , bite the bullet buy the Eotech !    

Medic-1, as I haven't a clue as to the style, or interest, of shooting that you practice, I'll just throw out what little I know.

The only "red-dot" optical sights I've used are the Aimpoint and the OKO. I like them both, but prefer the OKO because of the lighter weight, simpler package and lower profile. This isn't to say that I do not like the Aimpoint, I just can't seem to get along with it's control knob. Anyway, the OKO is an incredible little sight, very simple. Currently, I'm just awaiting the QD guard to become available, then I'll be set.

As for scopes (actually, what I'm putting on a PCR-16), I'm going with an IOR Valdada M2 with the Dragunov reticle. This scope has some incredible features and the quality, from I've seen, especially at a mere $360, seems to be available only on scopes costing twice as much or more. Anyway, with 4x magnification, the M2 is more than capable of handling anything .223/5.56 can.

Good luck.