Both are accurate but made for different shooting, the American is more of a hunting type rifle while the Varmint is more brench/varmint type. The accuracy should be basically the same, if you shoot a lot and fast the heavier barrel will be better, for hunting the American would be better.
I like the feel of the Varmint better, got it in 17 Mach2, 22 LR, 22 WMR, 17 HMR.