They definitely each have their own strengths and weaknesses, if I had to pick a winner, I'm going with Steam Deck, you just can't compete with their controller API and the Deck's assortment of input options; that alone makes everything else obsolete.
Raw horsepower(Rog v Deck) is a meaningless metric; Using the Rog is like driving a 911 without tires, just rims; you literally can't control it.
I have been considering a switch to the Ally. I agree that the Deck has more input options built-in, but there are several games I've been aching to play that aren't supported in Proton(and don't load on the Deck, I tried). I also would like to install Battle.net and play Diablo IV.
I realize there are hacks and workarounds to get a lot of things working on the Steam Deck, but I want to play games, not spend an evening doing Google searches and troubleshooting.
Yeah, but you can just install windows on the deck. OS compatibility arguments aren't really valid(no intentional offense), since at the end of the day.... these are just pocket PCs.
I will say tho, the switch is def the most limited. I think if you're in the market for a good handheld in 2023 and love Nintendo games, pick the rog(if you know your way around emulation)
I know this literally contradicts your last sentence, but I got Diablo IV up and running on desktop Linux really easily and it runs great. I followed these instructions minus the ProtonUp-Qt part (Proton Experimental runs it): https://www.gamingonlinux.com/2023/03/heres-how-to-run-diablo-4-on-steam-deck/
It amounts to: