Tales of Destiny DC does not have the most refined battle system. If we're comparing battle systems, I'd say either Vesperia or Xillia have the most refined ones to date. As much as I enjoy Destiny's battle system, it is not the best. I agree it's fun but when you have to rely on using BCs for a majority of the game during Chaos mode it's just BS. Bosses are a walk in the cake most of the time and are much easier compared to when fighting a horde of enemies.
Story-wise, I'd probably put Symphonia up there as the best, otherwise Phantasia/Eternia still.
But I kind of hoped that such a thread didn't exist since I don't really like to talk about and compare Tales games and what not. Tales fans should love all Tales games regardless. (Except Tales of the Tempest. That was horrendous. Quite.)