Based on your description, I think you’d be best off with the Ally, as it is the straightforward choice for a strong focus on AAA games. VRR and a bit more graphics power, no problem with launchers or anti cheat systems, and no need for control options since they are generally made for gamepad.
They’re both great, but I decided to stick with the Le-Go.
The bigger screen makes a number of games with small text much more enjoyable.
The ability to detach the controllers and independently position each hand and the screen can be way more comfortable /ergonomic than any standard handheld.
Relatedly, the ability to easily rotate the screen and stand it up with the kickstand has been wonderful for rediscovering pinball games and vertical arcade shmups in their intended aspect ratio.
Easy access to the Game Pass library.
That said, it’s got plenty of its own issues. Many are or will be fixable in software. But it will never catch up in battery life, and I do miss the trackpads, even though the mouse mode is better in some situations/games.
You can’t go wrong with either one, though, and I’m glad that the handheld gaming PC market has multiple good options.