If you're into open world stuff (which I totally understand if you aren't) the inFamous games are pretty fun. GTA with electricity superpowers and a *very* binary karma system, and stories that are so-so for most of the way, but with spectacular finishes. I like them a lot (more than Uncharted) but I get that they're not for everyone. They're my second- and third-favorite open world games behind Red Dead Redemption (which you should also play if you haven't on the 360 already).
Of the two Tales Of games on PS3, I think that Graces has more deliberate, strategic combat and Xillia has faster, more traditional Tales combat with fancier combos. Both games are pretty good, and Xillia 2 is coming out in English-speaking territories later this year. I didn't finish either game, but I liked Xillia a little more than Graces.
Second the recommendation for Valkyria Chronicles. That game rules. I wish that it had PSN Trophy support, but there's a built-in achievement system that is basically the same.
Now I have no idea if you like platformers or not, but if you do then you absolutely should play Ratchet & Clank Future: Tools of Destruction and R&CF: A Crack in Time. Crack is better than Tools (heh...), but they're both great jumpy-shooty-explody games. The download-only interim game, R&CF: Quest for Booty, isn't very good. But I love almost the whole series; R&C has basically been my Mega Man replacement since 2003.
And hey, if you didn't play them on PS2, get the Ico / Shadow of the Colossus HD Collection. Hell of a double feature.