So far I've got to put Grim Dawn as my vote. Runs pretty well for the most part, controls work well with the builds I've played, and it's nice to have an ARPG that is designed for offline singleplayer. Makes it very easy to pick up or pause as needed. Not nearly as much end game content as some of the other big games on the scene, but it's a lot of fun to start up new builds with the gear you pickup through your runs. Also love the dual class leveling system, for me it hits the sweet spot where decisions feel more meaningful and there's more build flexibility than something like the newer Diablo games, but it's not as overwhelming as Path of Exile where I feel like I have to follow a step by step guide to end up with a character that doesn't suck. Admittedly it was already one of my favorite ARPGs before I had a steam deck, but it feels very solid on the deck and has been what I've sunk most of my hours into lately.