Review from a RPG fan ^^
I have always played RPG games, since PSONE up to PS3. This love started with Final Fantasy 7 (best RPG ever in my opinion). But this opinion changed after i played XENOGEARS. Now i dont have a favorite rpg, i have TWO favorites. There are many reasons to love xenogears, here are some of them:

The game soundtrack is FABOLOUS! Yasunori mitsuda (responsable for xenogears OST) is a genius, just like Nobuo Uematsu (final fantasy OST)

The story just dont let you turn off your game, you always want to play to know what will happen next.

Anyway, in my opinion, this is the best ever, together with final fantasy 7 of course.