I also go back to Skyrim constantly; it is probably my most played game. I have a hard time making a definite suggestion because I sit here many nights and wonder which game I want to play and frequently find that I don't want to play any of them (so I scroll Lemmy instead). That said, below are a few that might be possibilities and I'm looking forward to reading everyone else's suggestions so I can find my next game too!

You could check out the Dungeon Siege or Torchlight series. They're both Diablo-style gameplay, but in a super generic RPG setting. They're both older, cheaper, and okay game series.

The Overlord series is fun, its kind of a reverse RPG where you are the bad guy terrorizing the locals with your minions. The gameplay mainly revolves around directing your minions more than direct combat. It is a bit simplistic, but I really enjoyed it.

I'm not a fan of the Witcher series, but lots of people love it and it seems to check most of the boxes you're looking for.

I agree with the Oblivion suggestion. I'm always conflicted on this one because I think it is a better game than Skyrim in terms of quests and interactions, but the gameplay is a bit dated and there were some questionable design decisions that resulted in some major overhaul mods being built to completely redesign the leveling system. I would love to have Oblivion, but with Skyrim graphics and mechanics (mostly).

Kingdoms of Amalur definitely seems like it hits everything on your list. I struggled to stay interested in it long enough to finish it (I think I finished it), but I'm not sure why since it has all the elements I enjoy from other games.

Similar to KoA, Dragon's Dogma seems to have all the typical things I like in a game, but I've played it twice and not made it out of the starting region either time. I'm not sure what it is that causes me to lose interest so fast. There's nothing I can point to and say I dislike.

Greedfall is super weird (to me) and not quite a fantasy RPG, more like medieval fantasy RPG. It is generally an open world game, but not as open as Skyrim (fewer side-quests, semi-linear main quest line). I thought it was an okay game, the main thing that frustrated me is that there were some areas of the game where you could make decisions with major story impacts and other areas where you were not given any choice in the narrative. As a result, I sometimes felt like my character was taking actions that were not in alignment with the narrative I had created for him. I appreciated that the game seemed unique and not just copying something else that was successful and I think I played it on GamePass at the time, so it was kind of like playing it for free. :)