Haha. I am a total Tales of fanboy. >___<
So of course: Tales > Star Ocean > Final Fantasy
My judgment is based on that Gameplay > Characters > Setting > Plot > Graphics.
After playing SO3, I couldn't go back to turn based RPGs (excluding Persona 3), only unless they were tactical (Advance Wars, FF Tactics, etc.) and I never really enjoyed any of the main FF games, so that left it in the dust.
The only problem I had with SO3 (the only SO game I've played) was that there was too much of a medieval theme even though it's sci-fi. (I'm not a fan of most medieval stuff).
Tales, even though the setting is something I dislike, is made of win. The plots aren't anything special. But the characters are what hook me onto the series, even though some of them are quite cliche. Unlike the other two series, I actually cared about the characters in the Tales games. And also unlike FF, the newer main Tales games get better and better. (Vesperia > Abyss > Symphonia ? Legendia, etc.) Although that's ultimately up to personal opinion.
Another thing that Tales wins at is that it actually makes me want to replay it from the beginning, which is something I hardly ever do with any RPG.
TL;DR Version:
1. Tales - Awesome Characters/Battle System/Content/Replay Value
2. Star Ocean (3) - Battle System/Content
3. Final Fantasy - Cool characters/Nice CG cutscenes