The best retro gaming console is the one you already own. Any old hand-me-down or thrift office PC can handle the majority of retro titles, as can most consoles with custom firmware.
If you already own anything from the DS-3DS-PSP-Vita lineups you should be looking into making the most of the hardware you already own.
That being said, my partner is very happy with their Deck, and I’m pretty pleased with my RG351V running ArkOS. I’ve also been very happy with running my RP3B+ with Retropie.
But to be very honest, I don’t do a damn thing that my gaming PC two builds ago, and my PSP1000 I’ve had since high school wouldn’t be able to handle with flying colors.