For me it's the Nintendo 3DS. Still have my white original 3DS from 11 years ago, jailbreaked it a year ago. I also played on my niece's DS as a kid, moslty Mario Kart DS, New Super Mario Bros. and Mario 64 DS. And Mega Man Star Force, the most impactful game in my life, is a DS game that I played on my 3DS. I'm very fond of the DS aesthetic.

The 3DS has plenty of good games on its own, but it can also play DS and GBA games natively, each with huge game libraries and lots of amazing titles. It can emulate NES, SNES and even Genesis pretty well too. The default UI is very pleasant and calming, it has a charm like the Wii and WiiU that became completely lost in the Switch. And the homebrew scene is super lively and still evolving.

I also just love the DS/3DS as a concept: it's the size of a smartphone and the clamshell design is unique. With stuff like a camera, internet access and other function, it was like a prototypical smartphone in some ways. I want to see a modern take on the DS with a good camera, bigger screens and better hardware, so that it could replace a smartphone.

It of course can't handle more modern consoles, but for retro gaming it's great. And if the screens are too small you can always emulate on a pc or laptop. And it beats the Switch in pocketability.