My favorite class is probably the Psionicist from AD&D 2nd edition. I got the Psionicists Handbook, and really fell in love with the class. I really enjoyed the class supplements back from that time. I still think the AD&D 2nd edition books are my favorite of all time. Some times I used to just flip through and read about all the monsters, the Player's Handbook, and the Dungeon Masters Guide. The old blue text and many monochrome art bits from that time sparked my imagination, and I learned a lifelong love of the game.
I always played RPGs for the role-playing (as opposed to the dice-rolling or actual mechanics) so my favorite classic RPG class is the Druid. There was always something so flavorful about the nature-focused magician who could shapeshift or cast spells but held to specific tenets of the natural order.
Planescape: Torment. Love the story and characters. Stuck with me over all these years. The spiritual successor Torment: Tides of Numenera was also good, but not quite Planescape levels. Black Geyser's looking to be able to hang with the classics!
Warrior/Fighter all the way for classic RPG classes. Something about being in game worlds full of magic and mighty monsters that you conquer with pure physical strength as a lowly human has always seemed super cool to me. Plus they always have the coolest looking gear.
My favorites have always been pure spellcasters like wizard, warlock etc. Just something about the flexibility/utility of spellcasting that makes me use them the most. Next would be rogue, because when you play RPGs with a party, you usually have to use the rogue as a scout, which means you spend a lot of time "controlling" them. Also for first person RPGs, it's always satisfying to have no door/chest/location barred from you. Finally would be ranger because, idk, bows are cool
I love monk, with the increased speed and not worrying if my sword gets taken away. Barring that I always loved being a paladin in Baldur's gate because they included a lot of cool things specifically for them.
My fav class is usually the bard, but because Black Geyser doesnt have bard class, i picked Necromancer instead. I named my character after a friend of mine called Edward, and im loving the class so far. It's able to summon much faster than what i could manually in any rpg. I like the Bard because of it's buffing and healing capabilities, and is able to sing to the party for even more attack and damage power. I hope they add in the bard after the game is finished.