I'm searching for a few new CRPGs to try, anything akin to the stuff I already enjoy. I will list what I already like below if you know of anything else? preferably on GoG if possible:

Ultima Series
Might and Magic 4-9 series
Certain Gold Box games (Anything from 91 on? or something like UA)
Wizardry 6-7

I also really enjoy Daggerfall Unity, Diablo II, Arx Fatalis, Ultima Underworld, Rogue, Thief 1, System Shock 2, etc. Also waiting for Severance BOD to return to GoG as well, hopefully.

I already have BG2, Risen, Rune, Return to Krondor, Hexen games, DOOM games, Wizardy 8 etc.

Just wondering if there are any other lesser known titles out there that I may have missed? I picked up the Hexen pack a few weeks ago and play a remastered version of that in a new engine, which I really enjoy as well. Just wondering if there are any other good series or packs on here that I can get that is similar to these titles, thanks.

There's Nox Archaist, which has a very similar engine to that of the Ultima series (specifically 4 and 5, but without the first person dungeons).

Perhaps it might be worth knowing which CRPGs you did *not* enjoy.

If you like CRPG/adventure hybrids, I strongly recommend the Quest for Glory pack.

You seem to like old school first-person RPGs, so have you played Ravenloft: Strahd's Possession or Lands of Lore? Those are two of my early faves of that type, from right when I got into PC games.

Disco Elysium, Land of Lore, Stonekeep, Die By The Sword, Titan Quest, Legend of Grimrock, Planescape Torment, Temple Of Elemental Evil, Divine Divinity, Divinity Original Sin, The Quest, Mount and Blade series, Wizards & Warriors and Drakensang, all on GOG!!!

Pillars of Eternity.

(Warning: Lots of text walls in this one.)

Pathfinder: Kingmaker
Dragon Age Origin.
Grim Dawn (ARPG)
Divinity Original Sin 1 and 2
Greedfall

Jeff Vogel has to be doing something right to have stayed in business for over 20 years, so I'm suggesting Exile/Avernum.

If you can get it running, Exile is free these days, and all his games have expansive Shareware demos so you can get to grips with them.

Finally finished my Tyranny playthrough, was fairly satisfying.
It wasn't made 100 years ago like the other games you mentioned though.

Personally, I think
https://www.gog.com/game/elminage_gothic
is better, and should be bought and played first.

Lands of Lore is great, at least the first one.

The first Witcher has rather old-school sensibilities so you might like it. It's one of my all time favorites.

Driftmoon is a very nice, charming game, also rather old-school though definitely much lighter and easier than those old games.

Ghost of a Tale isn't really a straight-up RPG, more like a adventure game/stealth/RPG hybrid, but it is easily the most unique, beautiful, charming game of the last decade, with remarkably good world building.

If you'd like to go more sci-fi, Deus Ex Human Revolution is fantastic game and holds up nicely. I recommend finding a mod for the Director's Cut that restores the original gold filter though. In this game, style matters.

The first Divinity: Original Sin is great fun. It doesn't exactly have a fantastic plot, but the gameplay in and out of combat is excellent, and the world is vibrant and entertaining.

If you like superheroes, especially older Marvel comics, try Freedom Force.

Wizards & Warriors is my recommendation

https://www.gog.com/game/wizards_warriors

David Bradley worked on this after Wizardry 6 & 7 so there are some similarities but it has it`s own unique elements as well, also has a great soundtrack.

final fantasy VI ( sadly only on steam )

Arkane Games (B/c you like Thief and System Shock series):
Dishonored series
Prey 2017

Loot-driven ARPG's (b/c you like Diablo 2):
Grim Dawn
Titan Quest

CRPG's (b/c you like BG2):
Neverwinter Nights: EE
Icewind Dale
Dragon Age: Origins - Ultimate Edition

Piranha Bytes' RPG's (b/c you like Risen):
Gothic 1+2+3
Risen 2+3