I would be curious about your favorite coop games. I often find them a big lacking, often being a bit unbalanced. An example is Battle for Hogwarts, where one game can be a walk in the park and another absolutely impossible and rarely is there a balanced match.
Spirit Island is really good as you can adjust the difficulty and it's always different
Stars of Akarios if you want a Gloomhaven Light Experience with some 7th Continent sprinkled in.
Seconding Spirit Island. It's quite possibly one of my favorite board games of all time (and a huge favorite in my regular play-group)!
Even in the base game, the amount of diversity in play styles between the spirits is incredible. It's absolutely a game that I could keep playing indefinitely and continue to discover new things.
Spirit Island is one of our favorite games of all time as well. It is for sure the most played game when it's just my partner and me. I agree it feels endlessly replayable with all of the variety.
We have also been playing through a homebrewed legacy system for Spirit Island that I found on reddit. Definitely imperfect but still super fun!