it all depends on what you like playing. imo, pretty much all of the classes are really fun, especially the mixed vocations (magick archer, mystic knight, assassin).
sorcery is fun to get into, especially if you have at least one other sorcerer with you that knows some of the same spells so you can do spell-syncing.
that guys youtube i linked earlier in the thread has some videos that go into each class thoroughly. the game gives you enough room to really do whatever you want.
btw, i would not start hard mode on a fresh save. it really was designed for ng + runs where you’re continuing your characters from before. stamina use and damage taken is doubled, and it’s really unpleasant if you don’t have some sort of leg up on it.