I'm in the market, what do you guys use, also do you prefer a 16" or 20" barrel, will it affect accuracy that much?

I don't own a .308 AR, but I do have a PTR91-K. I use it more as a brush busting gun, when large fields are around that open me up to the possibility of a longer shot. It has the 16 inch barrel. I find it "swings" well, but thats just me. What kind of terrain do you hunt in? Whats your preferred distance you try to shoot game at? Those would be two imporant factors to consider.

Our land is all hardwoods with a few food plots throughout it, max dist. is around 250yds.

Rock River LAR-8

LAR-8, AR10T

I'd go with a 16 inch barrel, and some sort of ballistic tip type round to ensure positive feeding(I don't know how finicky a .308 AR is, but an ounce of prevention....)

No AR 308 here, but keep in mind where you are hunting.  I have a 20" Rem 700 that is way easier to carry than my M1A.  Length can be a factor when waling through the brush.

If you are just looking for a hunting rig, given the environment you have described, I would recommend a DPMS 7.62 Sportical.

I hunted last year and this with a DPMS Panther AP-4 LR .308 with a 16" barrel.I have taken 3 deer so far. This rifle shoots .5" to .75" inch groups at 100yds with 150gr. federal fusions and it is a hammer on deer. All my shots were under 150yds and they never knew what hit them. I absolutely love this rifle. I have not had a failure of any kind with any ammo I have used. I have fired at least 1500 rds so far. The rifle seems to like anything you feed it from mil. surplus to high end target ammo and everything in between. I am saving now for the .338 fed. version as this would work on everything on this continent including the big bears. If your shots are 300yds or less the 16" barrel will serve you well and reduce carring weight. So far this year I have only gotten a doe but the season is just starting. She was DRT. at 80yds.

DPMS AP4 308

Using a LMT MWS(leupold mark 4 3.5-10x) this season with great success.
Two kills in 4days so far.
Using Hornady 165gr SST Super Proformance.

Me too, mine has a Millett 1-4x DMS-1 on it.

What about the new Remington R25?  Or should I go with a more traditional AR like the RR?

The remington R-25 IS A DPMS with a paint job and a name change. It also costs more with the remington badge. They are really nice looking guns but you will need to rework the trigger as with most STOCK panthers. I installed the the JP system including the lightning hammer and dramatically improved my groups and overall accuracy. I believe this one upgrade is responsable for the awsome accuracy I am achiving with my rifle and it is worth every penny you pay for it. You simply cannot go wrong with any DPMS variation you purchase and NO, I do not work for the company. I see alot of folks on here suggesting DPMS is a cheaper built, or not as well built as some other bigger name offerings. I do not believe a chrome lined bore and chamber is needed on a rifle that is not full auto. We needed this enhancement in VietNam but we also had full auto rifles in very extreme environments. I hope you don't have to sit in a wet hole full of red clay for weeks at a time to shoot a deer. I sure as hell hope they are not shooting back. I hope this helps you with a hard choice as the other suggestions are very good rifles as well.

split the difference i shoot a 18 inch DPMS that has a kreiger barrel and a badger rail. really stable and accurate.