FFX is pretty good, but i think the summoning system sucks. I hope FFX-2 is better. Kingdom Hearts is my favorite RPGs. Its integration of action, swordplay, and RPG elements, like leveling up and getting new abilities, makes it the most interactive and exciting RPG to date. It also has tons of extras like 4 hidden bosses, including Sephiroth. One of the coolest things about the game to me is the secret trailer for Kingdom Hearts 2 that you get for collecting all the Dalmations throughout the game. The graphics in the CG movies blow away anything in FFX. The music is really cool too. Besides the stupid characters (Donald and Goofy) and the gay world themes (under water in Atlantica? what were they thinking), this is one of the best games out there. If only there weren't so many Disney characters in the game and more FF characters. I hope KH 2 does something cool like make Cloud or Squall a member of your party. That would rule.
Peace.