I would go with the 22LR for target shooting. The 22LR is probably the most common short range bench rest caliber used.
If you are doing long range varmint hunting, then look for a 223 rifle. You can get a Savage Edge for about $300. About 30 years ago, the cost of 50 rounds of 22 WMR was close to the same as 50 rounds (2-1/2 boxes) of 223 Remington. The 223 was about $2.50 for a box of 20. Back then, you would have been better off with a 223 rifle for varmint shooting than the 22WMR.
Someone suggested the .17 rimfire. This is a good round, but it doesn't like a cross wind.
Savage edge w/scope http://www.savagearms.com/firearms/models/
If you are doing long range varmint hunting, then look for a 223 rifle. You can get a Savage Edge for about $300. About 30 years ago, the cost of 50 rounds of 22 WMR was close to the same as 50 rounds (2-1/2 boxes) of 223 Remington. The 223 was about $2.50 for a box of 20. Back then, you would have been better off with a 223 rifle for varmint shooting than the 22WMR.
Someone suggested the .17 rimfire. This is a good round, but it doesn't like a cross wind.
Savage edge w/scope http://www.savagearms.com/firearms/models/