If you liked Tales of Symphonia you should definitely check out Tales of the Abyss for PS2. As the name suggests it's part of the same series, and the battle system is pretty similar, albeit with a heavier emphasis on 3D movement. I don't think the story was as good as Symphonia's (though I've found that a lot of people hated that one for being unoriginal but meh), but it has a great cast of characters, especially Jade who is easily cooler than the entire cast of Symphonia combined.
You could also try Tales of Legendia, though the battle system in that game is fairly unexciting and pretty much just button mashing, and it has a different "feel" than the rest of the series. It does have an amazing soundtrack though, and the character quests really flesh out the backgrounds of all the party members.
For GC I have to recommend Skies of Arcadia Legends (assuming you can even find it nowadays), which is still my favorite RPG to this day. Has a very unique setting and atmosphere that's difficult to describe in words, and again a great cast. Also a heavy emphasis on discovery and adventure. The ship combat system is also pretty unique, I have never seen anything like it since.