If it were me, I'd opt for the .243 AI. Download it with 55-70gr bullets for the small stuff and use it for double duty on deer with 90-100gr bullets. Versatility is the name of the game. But thats just me.-Mike

If it doesn't bother you to have something a little more difficult to deal with (not much but a little) I'd go for the .22BR. My rifle has a 26" barrel and my working load runs 3650fps with 53's and I've had it to 3850fps without excessive pressure using AA2520. It's an incredibly accurate round. My second choice would be a .223WSSM just cuz I like short fat cartridges as well as the underdog in popularity.

I personally use a 22-250 for my varmit hunting, but if I was looking for another rifle, it would be the Ruger .204