In terms of cost effectiveness, .223 Rem takes the cake. For reach-out-fast with minimal recoil, the .22-250 is not bad at all! Some accuse it of needlessly ruining the pelt! But, if all you want to do is dispatch the critter...period, then it's pretty darned hard to locate a caliber that will out-do either the 6mm (.244) Rem or the .25-06 Rem.
Both the 6mm Rem and the .25-06 Rem offer near the same velocity as the .22-250, but maintain far greater down-range energy. Either can be set at zero on 300 yards, and are merely 4" low at 356 yards. That means, max point-blank aim is 356 yards with no worry of trajectory. Given the high B.C., drift will also be less. Just aim and fire!
I have used all of these, and many more. For certain, the 6mm Rem and the .25-06 Rem are authoritative, one-shot-kill masters of the varmint range. For what it is worth, either (70 grain 6mms), or (75 grain .257s) worked well. My preferred bullets were the Nosler Ballistic Tips! I also did well with Speer Hot Core Hollow Points. In the end, whatever firearm and cartridge combination you own can work, so long as you connect accurately, and with sufficient penetration. I have known several people who use their deer hunting rifle in order to keep themselves at peak capability, via this out-of-season real practice.