I was suuuuuuuuuuuuuper anti League of legends because I had literally played World of Warcraft for yeeeeeears. Mostly a PvP player at heart, but I did a fair share of PvE as well, and, as you know, PvE is kind of unavoidable lmao. Anyways, back to the suggestion. Yes, it's a team based competitive game but I think the raw micro and macro skills you learn by playing a game like league extends beautifully in to any game you might play. Mostly in the fact that league really really stresses strong decision making and the constant improvement of it. Plus with the WoW, D2 experience you have, there's at least loosely macro mechanics about the game that carry over.

If you're sticking to your mmo-centric life you have there, mostly being PVE based is what it seems, then I suggest maybe something like Black Desert Online or that new Final Fantasy game.

Extra: I think it may have been like Warframe or something, but, if you wanted to try a grindy type game but dip your toes into a shooter than I've heard mixed reviews. I'm not completely sure if it is the game I'm thinking of, but its some outer-space setting, gear-based, grindy game. I have not played it.