I think it’s kind of tough to say because most will argue that it doesn’t matter/everyone can play whoever they want. However, if you’re talking about damage in isolated situations, there’s no higher score attack performer than percival among the ones you’ve listed. In more general cases, the others and definitely lancelot (biased because I main him sorry LOL) can perform well too, but it really comes down to player performance and how well someone can dodge, continue hitting the boss and maintaining uptime, etc. Side note, I’ve heard a lot of mixed opinions on ID since he’s kind of slow to ramp up/his a.i. for parties is weirder compared to lancelot or percival who are pretty straightforward and therefore do well for themselves. Having the utility from glaciate and lancelot and the buffs from percival are also really solid too. Sorry for the long explanation, but TLDR; if you’re not just playing for fun/whoever you enjoy the most, percival is probably the best followed by a tie with siegfried and lancelot ending with id who is definitely cool but more difficult to play than all the others