Although i didn't quite like the characters and storyline of FFVIII at first (come on, an orphanage? =/ ), i later on enjoyed every little bit of that game. Ultimately, it had one of the more interesting developments story-wise, plus the Junction system being totally broken.
To say it in a nutshell, Final Fantasy VIII is one of the better ones, although i still don't like the fact that it's not classic medieval/fantasy styled, but that's just a personal preference.
Now FFX-2...... i could say it in one line:
Final Fantasy sequels. It never works. -_-
This game just held so many more flaws than i'ld expected. First, it's really an all girl thing, and the only thing that encourage me to play it, are still the amazing graphics.
I'm not saying there's something wrong with the gameplay, 'cause the dressphere system is quite good, but in my opinion nothing compared to it previous version in FFX. And the story and its characters....slim to none. I detested the different endings just a little too much to enjoy the game in its whole.
So in conclusion, an obvious result:
FFVIII > FFX-2