FFX imo is a superior game. The battle systems were both strong, I would have a slight preference for X-2 but it was a reasonable amount easier then X. This makes for me X's probably better. The storyline to X is far, far better and a more in depth comparison is silly because X-2 is so lacking in that department. Characterwise I prefered Rikku in X where she had a more serious side and I couldn't stand Paine giving X an easy win without having to actually compare. FFX-2 probably has better replay due to it's options throughout but I thin that's the only category it can be considered better in. Graphics in X-2 may be slightly better but not much and I prefer how they were used in X.

X is superior, easily.

And I do like X-2, around 7th on my list, admittedly there's a humongous gap between it and the next up and there are a few games very close to passing it but still that's a pretty high spot.