Have: Nwn2, NWN, Dragon Age Ultimate edition (also on Origin), Ghost of a tale , BG:EE, BG2:EE(Steam), IWD2, Trine Enhanced Edition, Trine 2, Pillars of eternity and its dlc, Age of wonders 3, Witcher:EE, Divinity: Original Sin 2 (steam), Drakensang 1 and Drakensang: River of Time, (steam), Crusaders Kings 2 (steam), medieval 2 total war (old cd key, my brother also owns it on steam ), Zeus and Acropolis (old cd key) ...

What next...

My personal recommendations:

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

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

I suggest Dragon Age Origin. It's very much a classic party-based rpg with Bioware's interpersonal dynamics added on top. Not quite what I would call "open world." But hub-like construction. You have to gain the alliance of 5 (?) factions. So you have 5 main quests. Within each, there are lots of side quests. A nice thing about this game is the variety of "origins." In fact, it is worth playing the origin of each variation possible. That alone is worth probably 10 (?) hours of play. But you'll probably play 1-3 before you really like one and you'll go with that one. I like this game a lot. It is difficult enough to be challenging. And it remains a thinker's rpg, rather than an action rpg.

Witcher 3 GOTY Edition - https://www.gog.com/game/the_witcher_3_wild_hunt_game_of_the_year_edition

Risen - https://www.gog.com/game/risen

Guacamelee! Super Turbo Championship Edition - https://www.gog.com/game/guacamelee_super_turbo_championship_edition

Before you buy that game, there is one thing you should know first:

The game requires lots of inputs at the same time, as there are many special moves you get, many of which require multiple inputs, and many which are usable once per jump; sometimes you need to use them all in one jump, and sometimes you need to worry about other things as well. This can make things difficult, but the more important implications are as follows:
* The game pretty much *requires* a controller. Playing with a keyboard, while technically possible, is not so easy, and some keyboards (especially those on laptops) have a limit to the number of simultaneous key presses they can handle at once (and this game is going to push, or perhaps even exceed, that limit).
* If you are disabled in a manner that prevents you from using one of your hands, this game isn't for you. (This should only affect a small number of players, but it is important to be aware of this *before* you purchase a game that you can't play.)

Aside from these factors, Guacamelee! is a good game, albeit not always fair. (Note that I have only played the Gold Edition, which also has an issue of not being colorblind-friendly.)

If you don't mind an old school recommendation, Ultima 7 is the game that set the bar for awesome RPGs...


Enjoy!

Personally, I think Ultima 7 has major flaws; the combat is horrible, the inventory system is horrible, and you have to use the inventory system to manually feed your characters when they get hungry.

If you are interested in the Ultima series, I would suggest the second trilogy (4-6) instead. The games have their flaws (some quite irritating), but at least they have functional combat and food is handled in a less invasive way. Also, the inventory systems aren't as bad (in 4 and 5 you don't even need to worry about it, as your inventory is infinite).

You have "Medieval 2 total war". You do not need anything next.

Anyway, I see a lot of fantasy RPGs but no "Planescape", no "Arcanum", no "Gothic 2" and no "Morrowind". How does this even work ?

And don't get me started on the "Fallout" series, which dwarves them all...

i hate the fallout games but I'm weird

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

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

https://www.gog.com/game/disciples_2_gold

Silver

As others already suggested, Nox and Titan Quest are good games. Arcanum is great too, but kinda buggy, from what I remember. The Withcer 2 & 3, UnderRail, which is similar to Fallout series, that you should probably try
Grim Dawn, Torchlight 1 & 2, Victor Vran for ARPG games.
And all-time masterpieces: Sacrifice and Giants: Citizen Kabuto.

Crusader Kings 2: Game of Thrones mod? :P

Seeing your collection of fantasy RPG's and platformers like Trine makes me wonder, would you be interested in Quest for Glory - RPG hybrid with point and click adventure game?

If you want something a little different, you could, of course, try Undertale.