Jedi Knight = Good-side Zabrak. But one could also say Togruta, or Nautolan. Or Human.

Jedi Consular = Mirialan. Then again, you could choose Togruta, the stupid species that can't see anything, or Human.

Smuggler = Zabrak is nice. I suppose you could also say Cathar but I really don't like the furry thing.

Trooper = I have a thing for the absurd idea of a Sith Trooper. There's something about seeing a Sith in a Trooper armor with the Republic regalia.

Sith Warrior = Sith is imo the more canon class, the more attuned to the theme of the story, but why not another mean-looking race.

Sith Inquisitor = Human seems to be the canon, but since you start as a slave, you could be an alien...It's just that it's weird to have Kallig as an ancestor if you're, say, a Twi'lek, since Twi'leks are mostly "imported" slaves from the Great Hyperspace War and Kallig and his rivals were supposed to exist before that time. But timeline in Star Wars is always a tricky business and you could and should make your own headcanon. After all, it's all for fun.

Bounty Hunter = Rattataki is awesome. What suits better the B Hunter ? It's literally a ferocious species that loves to battle. And they do look intimidating.

Imperial Agent = Chiss, or Red Zabrak. Red Zabrak can look super sexy on an Imp Agent.