Not a dig at yourself but your post made me think about why these mini systems are popular...
Retropie's, and all those other high end emulation solutions are great and the superior option to the "quick fix" ones that SNK, Sega and all have given us BUT (and this is certainly the case for myself) the charm of those mini systems is in no small part (hurrrr hurrr) due to their aesthetic. There's something a bit cold and sterile about those other more sophisticated options and even with all the custom casings, etc, in place they don't quite look, or feel, the part.
Absolutely man, the controllers especially are quite cool to have, they are very good quality and feel almost the same as the originals from back then. Also, Retropie is basically the same as the minis, the Playstation Classic is almost the same as Raspberry Pi 3 in terms of performance, while the other minis are a bit lower. The only high-end stuff for emulation is a powerful PC, only then you can have good shaders and run very accurate cores.
These mini consoles definitely have their charm, and do what they are meant to quite well, but on stock settings and with the original game lineup I find them laughable at best. Can't speak for the others since I don't have them, but the Playstation Classic was quite a huge disappointment, poor emulation, PAL50 games, no custom overlays and scanlines, shit game lineup etc. Everything was fixed by the community and if you tinker with it it can be a more than decent emulation machine.