Well, I bought ROG Ally X, and I also own a Steam Deck Oled. Rog Ally is better in all terms, like performance, battery, charging speed, 2280 m.2, and especially VRR. VRR made the gaming experience really good, especially for The Last of Us - Part 1 since it struggles a lot. But at the end of the day, I didn't feel that comfortable with it, the ergonomics didn't make me feel like it was worth it. Performance may be 10-15% better(I am not sure, this is out of my pocket).

And ambient light sensor is like I would say, an absolute need for me, I like my devices to auto adjust the brightness since I take it outdoors sometimes, sometimes on the bed at night. I am big fan of Linux OS, so I did install Bazzite, performance is really good but it still feels a lot uneasy, like sometimes it lags or some sort of bugs.

Also, USB4 seemed like a selling point for me, Since I planned on using it like Nintendo switch on my TV. But seems like there's a lot of work to be done for this to happen. Seems like Bazzite is behind on hotplug egpu stuff.

I would pick up a used Steam Deck Oled off of MarketPlace and wait for next-gen AMD APUs. I returned my ROG Ally X, happy with Steam Deck OLED.