I've bought the Abernic RG353M as a present for a friend who really wanted to play some retro games but is a bit a-technical, so I thought I'll do him a favor and load this device with a ton of games.
After reading into countless reviews praising the device I can only say I was utterly disappointed by the overall experience of it. I installed whatever firmware was needed, the process felt sloppy and the result being some unstable (Android-based?) OS. Half of the time the device wouldn't boot up and required a reboot.. then trying to play some ROMs on the device.. definitely skip anything 32-bit, though it claims it can play it, the FPS is too low to enjoy the game. Sticking to the usual 8/16-bit emulators and still it would freeze up, corrupt save states and whatnot.
The Retroflag GPi Case 2 using a Raspberry Pi Zero on the other hand.. flawless! I never had an issue with this device.. the OS is stable, I am using the first Pi Zero so I am not sure if later versions would run 32-bit emulators smoothly, but the first Pi Zero is at least capable of booting them up.