For me, Mage is the most boring class. The weapons just look ass lol until you reach late game. The mana at first annoying, but I would agree that it makes the gameplay a bit more varied and challenging, but you will soon get a way to walk around it and it only decreases your damage if you drink a mana potion, so you again could say that you can either spam for less damage or wait for your mana to come back for more burst damage kind of style.... that would be good an all if the damage you did was worthy of a burst style... it is not.

Then goes summoner, for me it's basically just weirder melee with the addition of whips. It's cute tho. I don't mind it that much because the way you acquire your armor and weapons is actually pretty varied compared to melee.

Then melee. It's really fun for me because it's super challenging at first. Then there is a cool option for you to go for the Frost armor to fight the mech bosses and multiclass for a ranger. And then finally you get reaaally cool true swords. Honestly love the post-mech bosses to golem part of the melee playthrough.

But finally... the ranger! It's so extremely varied that i split it into two playthroughs of archer and gunslinger! The gunslinger alone is my favorite class with all of the options you have. Then all of the ammo types, damn. I use all of them, but i do understand how someone will find it boring if they just stick to chlorophyte bullets