The Toxic will net you a few extra FPS due to the higher factory overclock, but the Vapor X might run a tiny bit quieter (not much).
If you're set on the Toxic, then you won't be disappointed if performance is your only concern, the Vapor X won't be significantly slower.
how about the dual-x. im leaning towards it since it's cheaper
It is cheaper because... it is a stock card which is not factory overclocked .. The + of the dual-x is the cooling.. the dual-x represents the 2 huge fans in the card