I like the "Anbernic RG35XX SP" because it feels like an upgraded GBA SP. It has a foldable screen so the screen doesn't get scratched while carrying it in my purse. And it has 2 micro SD card slots. One for the OS and one for games. Meaning you can customize it any way you want to.
I installed muOS on mine which even supports some "ports" of PC games. I love playing Stardew Valley on it for example. Though it does take some tech knowledge and research to figure out how to setup.
The buttons are nice and clicky. And granted, the 35XX SP doesn't have analog sticks... But IMO, analog sticks always end up in weird spots on smaller clamshell handhelds. And I have other devices where I can play those kinds of games. So it works for me.
Its also nice and light. Larger handhelds like the steam deck are too heavy in my opinion. Heck I even have trobule with the switch sometimes and the 3DS XL haha. Maybe it's just cause I'm getting old but those kinds of handhelds hurt my hands and wrists when I play them for more than an hour or so. But I can play on my RG35XX SP all day without any issues.
It does come with default software and a bunch of games. Which could be nice if you're less tech savvy. But I personally like to remove all that stuff because I want MY games loaded on to the device and not a bunch of extra stuff I might not play.
Anbernic makes a lot of good devices so I guess it's more of your personal preference. Maybe checkout some comparison videos on YouTube and see what you like ;-)