Class definitely matters, on my mage I found bosses harder (In that you died quickly if you messed up) but you could also beat them quickly.
On my cleric I found bosses to pose no threat whatsoever, I could in fact never dodge an attack and still win, but it took a while to bring bosses down with the only 1 real dps attack clerics get. (Zaibu I think it’s called.) This is assuming your smart enough to put a reasonable number of stats into con.
Warrior was middle of the road, bosses were fairly easy (But you still had to dodge stuff) and bosses died at a reasonable pace. (I’m told different warrior builds have overpowered damage which vastly exceeds mages, I didn’t have one of those builds for testing.)
Haven’t tried archers.
(This is all sub lvl 50 content)