Chrono Trigger is one of the few games that I consider to be as close to perfect as anything made by mortal man.
The plot is fabulous. A group of teenagers are accidentally sent through time, and discover that the world will be destroyed in the distant by an evil entity called Lavos. What follows is a time-travelling epic, as the teenager travel through the ages, attempting to learn Lavos's origin and how to kill it. The time-travelling premise gives way to lots of options, sidequests, and secrets. For instance, you could take an item from a chest, but if you leave it there and come back 1000 years later, it will be a better item.
One of the many great things about Chrono Trigger is its combo attack system. In battle, you can combine the powers of two (and sometimes all three) of your party members, so there is a nice strategic element in deciding who you have in your party.
And here's the capper: NONE OF THOSE DAMN RANDOM ENCOUNTERS THAT PLAGUED THE FINAL FANTASY SERIES!!!
This game is now available on PS1 as part of the FF Anthology, hence it is available on PS2, hence all those people who can't shut up about Cloud and Sephiroth should go and play it. If they do, they'll be talking about Crono and Magis instead.