I'm considering, at some point:
Astral Chain (because the the gameplay looks cool, albeit potentially a little too fast paced for me)
Divinity 2 (because I haven't played it and the reviews are out of the world)
Mario + Rabbids Kingdom Battle (because I love the XCom games
Fire Emblem: Three Houses (because I love the series)
Bloodstained (because the reviews are very positive for other platforms and I like Castlevania, so I'm willing to wait for them to fix up the Switch port)
Already have:
Zelda (finished it)
Mario Kart 8
Smash Bros
Arms
I'd think about Galaxy, but it seems like too big an investment of time when I already have two guaranteed time sinks on the list, plus I imagine I might be tempted to get The Witcher 3 when it's out later as well.