There’s a good discussion on the Thoth Vs Domitia debate over here: Thoth Amun or Domitia?
And another thread about Quintus here: Thoughts on Quintus after his last update
I’ve chosen Thoth over Domitia; Quintus wasn’t an option for me. Thoth deals much more damage than Domitia, and his minions can save they day in a raid by inflicting damage without giving mana to the foe. Minion animation makes him unsuitable for Challenge Events if you intend to be top 50.
I like that Quintus doesn’t rely any fancy mechanics to do his damage. Like Lianna he dishes out a huge amount of damage, period. I’m not a big fan of slow mana, though it does mean that when finally fires, it’s lights-out for some of his foes.