I plan on doing a write-up on the Mi Box S and emulation later this week, but in short, it blew my (low) expectations away. Of course it handles 8bit and 16bit games well, but I didn't think PSOne and PSP would play almost perfectly, but they do. Nintendo 64 isn't emulated well on any platform, but I've completed Super Smash Bros and Mario Kart 64 without issue on the S. I use Retroarch for most systems, PPSSPP standalone app (available on the Play Store) for PSP, and Mupen64Plus AE 3.0.187.

An older version of Mupen is on the Play Store, but the latest version you'll need to side load. But to be honest, I haven't noticed much of a difference between the two. Only issue I've been having is every Mupen graphics plugin ceases to work after a while, so I have to clear the app's data to get everything working again, losing my library and preferences in the process. Save states/data are preserved, however, so I only really lose a few minutes of my time whenever this happens.

I'm talking about Nintendo 64 so much because believe it or not, it's why I bought the MiBox S! For me to play N64 games to play through my OSSC upscaler, I would've been out $200+ just for the N64 mod and cable, so I took a $40 risk on the S and to my surprise, it paid off. I want to reiterate that just about everything else plays flawlessly. If GameBoy, SNES, Genesis, and NES are your primary interests, I can't see you ever running into any issues. I know you said you only wanted to do a bit of emulation, so since I'm new to AndroidTV and have only been into emulation, I thought I'd cover my overall experience with the S.

I have both. MiBox is miles better.

I have three MiBoxes with 1080p displays (two dumb TVs with original remotes, and a videoprojector + 5.1 AVR + Harmony Ultimate) that I use with IPTV (Molotov TV here in France), Kodi (through samba shares), Netflix, Amazon Prime, YouTube, and Retroarch.

It works perfectly, no bug nor freeze since the last OS upgrade, early November. Note that I don't use WiFi, but UGreen Rj45 adaptors.

I don't regret my investments in the Xiaomi boxes.

Mi Box S is better option. I have the original Mi Box and it works, no issue. I also bought a KM9 to test out S905X2 chipset, very disappoint about its system. KM9 uses an android 8.1 image compiled from Amlogic SDK, not officialy certified by Google and Netflix. I can sideload Netflix for Android TV but couldn't get Chromecast working. Besides all, the KM9's WiFi is not stable, occationally disconnected which I haven't seen in Mi Box after the recent Oreo updates.

Where can i get an mi box s or reg one? Im in canada and dont see where i can get one? Is it much better than the fire stick? Reg or 4k?

Assuming you live in a country where it's not possible to buy a Fire stick, otherwise your picks just make no sense, I'd think the Mi Box S is the safer choice and least bad of the two.

Netflix are having another crackdown on uncertified devices it seems, like the you see with Mecool devices.

Personally I would not run the risk if you want reliable 1080p Netflix App streaming.

DO NOT buy the unsupported Mecool KM8 - that device appears abandoned by Mecool.

I would get the FireTV Stick 4K over the Mi Box any day of the week, more powerful hardware and it's far better supported by Amazon than Xiaomi can ever hope to do. It also has really good MIMO AC WiFi:

https://forum.kodi.tv/showthread.php?tid=336151

You are likely to get better Apps support for Catchup TV in parts of Europe from Amazon Apps developers vs Android TV developers.

Good luck dealing with 24p Netflix content & then European 25/50fps content on a device like the Mi Box that has NO Auto Frame Rate Matching. Results will be video playback stutter city.