It sounds dumb but my pick would be the SNES. There’s just something about 16 bit games I love.
The SNES has so many good games, like sf2. The first party games and some good arcade ports.
It also has a lot of good RPGs, like chrono trigger
The controller is really cute
Tho, the PSP is a close second. Tekken dr running at 3x resolution looks beautiful
Yes I’m a sucker for dpad centric devices. Yes i love emulation.
16 bit stuff looks amazing
PSP, hands down. So many incredible games, it was a RPG powerhouse, that screen was great for the time and for me it was an “everything” device (I remember browsing the web and reading mangas on the PSP… Janky but incredible all the same).
The Vita comes close - nigh “home console” games on the go and the OLED screen to make those shine.