ok, AR guys. what kind of small game/varmint rounds fuction best in a standard ar 15 ?

Standard AR-15? Okay, what some people call small game others may call it medium game. IF you have a 1:7 twist and 16.1" barrel chambered for 5.56x45 then try Black Hills Ammunition 77 grain Sierra Match King hollow point. If you are possibly not satisfied then go to Hornady V-Max like others have suggested. The SMK may be a little rich for your blood but you are the one that said you wanted the "best".

Depends on if you reload or not, factory V-Max works wonders on most varmints,Barnes Varmint Grenades are great;what barrel twist you use might impact your ammo weight choice a little. While Mil style loads will work for some applications they aren't as accurate as "varmint" loads normally and don't have the same expansion profiles. There isn't "one" choice, you have to determine your accuracy needs and if you need extreme frangibility or something to punch holes into coyotes.

I think the Hornady V-Max rounds are a good choice, but an exact recommendation would depend on your rifle's twist rate, barrel length and what you intend to hunt.

We hand load 55 gr Nosler BTs. I don't know that they are the best, but they are good enough. I can't really say that any of our AR-15s are "standard".

55 grain and a 1:9 twist barrel

Hornady V-Max perform very well on my semi-auto and bolt action .223 caliber rifles.

I like the V-Max. In my opinion it is hard to beat.

All of them.