I own them all except Magna Carta 2. I can say that Lost Odyssey has the best storyline out of the bunch by far. as for gameplay, they're all about even...with Vesperia being slightly ahead. the Last Remnant has very interesting mechanics, but suffered from downright horrible framerate issues. Infinite Undiscovery was fun for what it's worth, had a decent plot and flashy combat. overall I'd say LO is the best.
another one I'd compare to these is Resonance of Fate. this game was one of my favorite rpgs this gen, mostly dude to how original the combat system was.
my game collection: http://www.gamespot.com/users/Tention/games_table?mode=own
LO's gameplay felt very dated and the characters were too rigid and unrelatable. The one thing I always hear LO praised for are the dream sequences, but I found it boring to read through pages and pages of text at a time.
ToV did a much better job of character building, but the overall story probably wasn't as good. I preferred its gameplay and cartoony art style over LO's overly serious tone and turn based combat.
Tales of Vesperia is probably my favorite out of that list. the gameplay and character is great. the visuals and sound design is solid(with it having probably the best voice acting in a jrpg) story is probably not as good but still ok.
I'm a gamer dang it, not a pc gamer or a console gamer, just a gamer.
I've never played Magna Carta II, so I can't include that one in my list. But, of the remaining four, I'd list them thusly:
1. Lost Odyssey = The most emotional game I've ever played. The story, while somewhat cliche, is worth playing through simply because of the "feels" alone. The gameplay is also solid, as it's very traditional.
2. Tales of Vesperia = I only played this a little bit and never beat it myself, but it seemed to be well put together and I know it receives lots of praise.
3. Infinite Undiscovery = Underrated, but still just an average game. It's pretty much the closest thing to Kingdom Hearts you'll find on the 360, but with horrible, horrible acting. Need to see what I'm talking about? YouTube "dinner dance". Eesh...
4. Last Remnant = The gameplay was very interesting, but ended up being the game's biggest downfall. Boss fights end up being much more difficult than they should be because of your inability to fully control your own team. The leveling system is a bit wonky too, as you could reach the end of the game with extremely weak characters (and be unable to boost their stats) if you don't pay attention to it.