Well, it's not really a mmorpg game (it have co-op elements), but if you maybe like anime and games in that style (and Zelda BotW), you could try Genshin Impact. It has a surprisingly big (and still expanded) world to explore, a lot of puzzles, etc. It could be a nice time sink.
For a traditional mmorpg, I could recommend Star Wars: The Old Republic - it has a really nice story with voice acting (every class has a different story). I was once looking for an mmo too, but nothing could catch my interest. This game actually did, even if it's old. If you like Star Wars, it's even better.
Sorry, I don't have any better recommendations :P
