Anyone who claims FF7 is the best RPG on the PS1 obviously hasn't played Xenogears.
The game centers around a mysterious and amnesiac protagonist named Fei Fong Wong who for whatever reason cant seem to remember anything of his past and lives in a small mountain town where he spends his days painting and living a normal happy life. A typical set up for any rpg, but less then an hour in you are in anything but normal RPG territory. Fei's town is eventually attacked by a group of military insurgents who are in the process of stealing a new and dangerous weapon. This weapon is what is called in the Xenogears universe as a "Gear". Basically a giant gundam-esque robot. After an attack from a different group of military insurgents, the stolen gear ends up in the hands of Fei who loses consciousness shortly after taking control of the gear and ends up destroying his own town and killing the people who took care of him for years. The story has its twists, turns, deceptions, surprises, and flows nicely throughout the first disc spanning a meaty 50+ hours on your first play through. This RPG is LONG but will keep you entertained from start to finish. You may even be left wanting more out of it towards the end. The music and graphics are really quite good for the PS1 and 1998. All environments are viewed from a top down angle and the camera can be rotated 360 degrees around each environment. The graphics blend 2D and 3D perfectly and even by today's standards are still really nice to look at. None of that ugly blocky 3D we saw in FF7. Combat alters between 2D and 3D. 2D being used for non-gear character combat and 3D being used for Gear based combat. Both systems work similarly and have little to no learning curve. Attacks are carried out by pressing button combinations such as X, X, Square. Deathblows are learned over the course of the game and are basically carried out the same way as normal attacks but offer a more flashier and damage inducing blow then the standard attack. The system ultimately keeps you involved and entertained and manages to make battles that much more exciting.
The game explores many interesting themes such as German philosophy, religious references, racism, and even cannibalism. The story is by far the strongest part of Xenogears and by and far the biggest reason to track down a copy of this game. There are also some excellent anime cutscenes though not nearly as much as you would hope. Xenogears is becoming increasingly rare and will cost you anywhere from $15 for a green label or upwards of $50 for a black label. If you ever come by a copy or are even slightly interested in playing a Squaresoft classic this is your game. Not to many people recognize and appreciate this game as much as it deserves but those who have experienced it respect it for what it is.
What is Xenogears? It's a damn masterpiece. Check out Xenosaga ep 1-3 if you enjoy this one.