I've played them all, and I must say, I like VII and after better than VI and before...except for the fact that after V challenge is something you have to look for.

I really liked X-2, and it's really shallow to just assume people who like it must just be ignorant of the pre-FFVII games. Infact, I think the originality was what I liked best about it. It also has the best battle system in my opinion.