Demon Souls/Dark Souls fans.

I usually like to go the high damage melee classes and build like a glass cannon, but with DS3 I just went mage and I can say it was a lot less frustrating and overal an easier time (than my playthrough DS2 was).

Why to prefer you a class you havnt fun with it? Start with the class you want to play and have fun.

Deprived.
I like starting from zero :P

I try to play all of the classes. First play through was a wanderer in Dark Souls.
It was tough, especially if you tried to play mobile. Any attack will stagger you, so groups are deadly.
Then I played a warrior. Ended up using a halberd and medium armor. Spin to win, baby.

Depends on the bonuses. Demon souls is whoever gets the master key ( I think it's called)

Classes aren't that important, but I usually go the knight or warrior, since you can never go wrong with a STR build. But I've tried the pyromancer for my SL1 run in DS1, and I admit that having pyromancy from the beginning is a huge bonus. In DS3, I start with the knight again and a fire gem, you can't imagine how useful a fire longsword is in the early game.

In Demon's Souls, I liked the Royalty class. Soul Arrow is fantastic for the early game, and lets you take down enemies you'd never stand a chance against otherwise. And Soul Level 1 is a nice bonus.

Like TBreaker said, classes only matter early in the game, and in DS1 pyromancer is the way to go if you want to have an easy start. It helps that pyromancy is useful for non-magic builds anyway.

Deprived, fist only runs.

Pyro for the fire on early game.

Depends on the game.

DS1 = Either Warrior, for quick access to Gravelord Sword, or Pyromancer, for the extra Fireball spell.
DS2 = Deprived, no reason not to start as one since there's no first boss barrier.
DS3 = Knight, it's more balanced than the rest (no useless points spent in Attunement and Luck). Assassin and Deprived are also solid choices. The rest has awful stats.

Knight because I'm an HP coward

I prefer knight, mostly because I play fashionsouls and it goes well with my preferable armor. Everything else can be acquired with some effort.