660ti as bigger memory bandwidth also more raw power. First number denotes generation second denotes tier level in generation. Ti just denotes a mid level between the two tiers where it is greater than the non ti of the same number, but lower than the next number up. I would say that for 300 usd the best for the money is gtx 770 which is slightly better than gtx 680. Second choice would be 760 for 250 as it is slightly better 660 ti with more memory bandwidth as the 660 ti is limited by it.. Out of the 3 above deffinetly 660 ti