I'm half through Xenogears, but haven't played it for 3-4 years now, and have sure a lot of others to play first.

Here is a list of the RPGs I have, and it's always upadted --> RPG list

I also played the Xenosaga trilogy, and it's really good. Only episode 2 has a less good battle system, but is still good, both others are very good. And if you begin to play, begin with episode 1, otherwise you won't understand the story, which is already very complex (I suppose you don't begin watching Star Wars episode V if you haven't seen any other yet).