Depending on the console, the most important factor is the games selection on the console

If you're talking about a handheld PC like a RoG Ally, then it comes down to ergonomics and possibly build quality & support by the manufacturers.

I have a RoG Ally 1st gen and I love it. Asus just released a mid-gen refresh in the Ally X and both seem to have been selling well so I can definitely see them releasing an Ally 2 in a year or so. That might be when I upgrade......