I'm by no means an Analogue fanboy, but the Analogue Pocket would be my pick. The screen filter/emulation on the super-high-res screen, super low latency, portability with dockable functionality, retro form factor, and it covers all the systems that are "retro" in my mind (pre-PS1). I think others may prefer a Steam Deck or Odin or other more powerful handheld to emulate better systems or have more seamless save states.