Steam

I love colony sims, factory/automation games, city builders, CRPGs. OpenTTD, OpenRCT2, Rimworld, Prison Architect, Factorio, Shapez 2... anything that heavily replies upon a mouse on PC, and is finicky to control with thumb sticks, is remarkable with the Deck's track pads. I've also got a handful of desktop apps, added as non-steam games so they can be accessed in gaming mode, that benefit from track pads. I like being able to open a browser and flip toggles in Home Assistant or access the web UI for other things I host.

I also like to dock my Deck and my Pro 2 controllers (great for fighters, platformers and classic console emulation) aren't gonna cut it for those games. The steam controller looks like I'd get everything I love about the Deck's controls - while docked. That's a big deal to me. Maybe I'll get lucky and actually be able to snag one this year.

If you don't play anything in those genres or never drop to desktop mode, you're probably not missing anything. But I intentionally bought a portable computer and frequently use it like one.