I've never played Abyss. Which is why I'm so pissed I can't find it. xD
As for Legendia, it's got a better plotline than Symphonia, the character classes are completely different (the main character is Senel Coolidge, a Fighter, the Swordsman is Chloe Valens, a chick for once, and there's Jay, a ninja-like kid. There's a girl named Grune with very powerful magic whose weapon is a jar and there's a spear user named Moses Sandor, who's good at ranged attacks and is pretty effective against aerial enemies. He's my personal favorite character. There's three other magic casters, Shirley Fennes, Senel's little sister who isn't available until after you beat the main storyline, Norma Beatty, a healer with offensive magic capabilities and Will Raynard, an offensive magic user with healing capabilities. Will's my second favorite character pretty much because he was voiced by the same guy who did Kratos. xD), and the Techs (called Eres in this game. I have no idea why they have to change it every f-cking game) are pretty damn good. There's also a way to combine Eres and create new ones. Throws are also introduced via Senel. Throws are Eres that can be used on an enemy when they're down (like after Beast) for additional damage, and they do quite a bit of damage.
However, the system of gaining the techs can be a huge pain in the ass. For magic techs (or crystal eres), you have to find things called Eres Stones, they're found by beating enemies, and finding them during battle isn't guaranteed. Also, the game is pretty damn short. I killed off 90 percent of the plot over a 20 hour period, but there's character quests and additional stuff like that after you beat the game, which I haven't done yet since I accidentally deleted my file off my PS2 Memory Card right before I beat the game (cue explosive swearing and damn near a hole in the wall), but I do have the guide, so that's how I know about those. xD