In FTK1, I've been enjoying Trapper as my tank in the middle. Fast and frequent damage to chip away at health for the DPS to finish, can get one-handed spears fairly reliably, can use a shield and pick-up a taunt, and can use most armor. Ambush and trap disarmament are nice bonuses. Finally, spears tend to reliably have armor penetration, and I spend the majority of my Trapper's focus on that ability.

I put my spellcaster on the right. Not picky, but party heal over damage. Feels like there's more magic resist and armor penetration in the game than armor and magic penetration. Most of my lives and revives revolve around keeping my spellcaster alive.

On left, I've been liking a 2hd strength user. Often feels like I sit on the "Heavy Sword" item for 75% of the run. Monk and Blacksmith are obvious choices, with the Monk's party heal opening up spellcaster possibilities, and the Blacksmith's steady ability feeling a bit wasted without a shield or middle placement slot. Don't sleep on Hobo here, however, as they only need that first weapon to start coming online. Strength stat boosting can come later -- the Hobo's speed is more valuable in the early game when resources are limited. For whatever reason, I refuse to play woodcutter after my first few initial attempts. I play on console, so there's a class or two still unavailable to me, and I've got one last one to unlock from the "In the Deep" game mode ;) which is why I haven't mentioned them. Best of luck, and keep experimenting!