I've been trying to decide which upper to put on the lower I already have.  I think I've narrowed it down to one of these:
http://aresarmor.com/store/Item/aa_BAupper
http://www.bravocompanyusa.com/ProductDetails.asp?ProductCode=BCM-URG-18-SS410
http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=569

I'll be using the gun for groundhogs (out to 250 yards or so) and squirrels (75 to 100-yard head shots) so accuracy is very important.  I'm also concerned with weight -- the lighter the better, reliability, and cost.  I'll probably put a Nikon P223 3-9x40 scope on the rifle.

Anyway, I'd appreciate input on choosing my upper assembly.

Thanks!

BCM.

Why the BCM?  Just curious as to your rationale for the recommendation.

Probably because it's one where "you can't go wrong". Added to the deal I believe they are still running  which includes a free FH, bcg, and cgarging handle, BCM really isnt a bad buy now.

I have bought stuff from Ares armor, and although I had a problem free transaction,  I am hesitant to order from them usually.  They lack a lot of specs and details for their stuff online.... On the other hand, Their prices are hard to beat sometimes.

BCM is clearly a the best option of the three you linked.  You should go with one of their 16" ELW (new profile) and get a free BCM BCG and free muzzle device, right from the BCM site.  You will not gain any precision going longer than 16 (length is not = precision) it will just add weight up front, making it a less enjoyable and slower pointing rifle.  Link below to optimal solution:

http://www.bravocompanyusa.com/BCM-16-Mid-Length-LIGHT-WEIGHT-KeyMod-KMR13-p/bcm-urg-mid-16elw-kmr13.htm

Despite some bad press re shipping in the past, I've built 5 ar's using PSA uppers and have been really pleased with them. So far they have all been very accurate and reliable. Try this one for example:
http://palmettostatearmory.com/index.php/ar-15-05/barreled-upper-assemblies/psa-16-chf-stainless-steel-5-56-1-7-lw-ssk12-upper-without-bcg-or-ch.html
I believe many of their barrels actually come from the FN factory that's nearby.

This is why BCM.

I haven't yet decided whether you guys fall under the "good influence" or "bad influence" category , but this is what I got: http://www.bravocompanyusa.com/ProductDetails.asp?ProductCode=BCM-URG-MID-16ELW-KMR15 since the upper with the 13" KMR handguard was out of stock when I ordered. I added a Mod 3 (large) CH and a forward grip.  BCM was even good enough to respond -- on Black Friday afternoon -- to my exasperated, snarky email after their site kept telling me that my email addresses weren't valid.  They fixed the problem and I was able to complete the order.

Thanks again for the input and suggestions!