I know this is late but so far I’ve been enjoying my c2 Sorcerer and it makes it easier to get your Summon to keep damage on a boss since you can tell it to stand near it while you keep out of reach of all the nasty AoE attacks many of them have. c1 Sorcerer can work though if you are going that route then it’s best to go c2 Necromancer and make sure you aren’t going glass cannon otherwise you’ll die since you’ll be mid to close range of bosses. Also getting hit and moving a bit too far from your target will make your summon stop attacking and walk towards you taking away your dps and wasting precious sp.
Also to note, some of the bosses have some rather powerful skills that can be utilized by riding them but you don’t have access to them unless you do go c2.