IMO Steam Deck is the best overall option, as it's beefy enough to run PS3 or even Switch games.

If it's too heavy, the Retroid Pocket 3+ is a decent emulation competitor with a lighter, smaller form factor.

I find myself constantly switching between them all and can’t settle down to actually play a game.

This sounds like one of those problems where buying more hardware doesn't help. Ruminating about the "best" handheld choice is an easy way to forget about playing the games themselves. I've been there. The solution is to just pick a device at random, and go outside to play it. There will be pros and cons, but if you're not even getting to the point where you can actually play the game, then the pros and cons don't matter either.