Most have already said the best ones :) Valkyrie Profile, Tales of Eternia, and Brave Story are all awesome. My three favorite (in that order) behind Crisis Core
For something different: If you are looking for a turn based monster battling rpg (think pokemon with a better everything lol), I suggest Monster Kingdom: Jewel Summoner. Also, Legend of Heroes is a pretty decent turn based rpg, but not as good as the three I mentioned at the top.
Top 10 for me would be: 1. Crisis Core Final Fantasy VII 2. Valkyrie Profile Lenneth 3. Tales of Eternia 4. God of War Chains of Olympus 5. Final Fantasy Tactics War of the Lions 6. Brave Story New Traveler 7. Monster Kingdom Jewel Summoner 8. Daxter 9. Ratchet and Clank 10. Patapon