[Matis]

As far as I know, Tales of the Abyss has a battle system similar to Symphonia, but improved. Don't take my word for it, though.

I've only played the GBA, GBC, SNES and PSX games, so I can't comment on the newer ones, but...

I've heard that the PS2 remake of Destiny and the PS2 Destiny 2 have actually the best battle system in the series, it being very fast paced and actually very hard too.

Still, from the ones I played(all of the ones available for the consoles listed above, bar Summoner's Lineage for GBA), I must say that Tales of Eternia is by far the best of them, with Narikiri Dungeon 2-3 coming close in battle system and Phantasia having the best story and most likable characters of them all.