I've only had experience with the Formuler Z7+. The MyTVOnline app is probably the best IPTV software I've used. The only issue I have with the Z7+ is the wifi -- its not very good, but I'm not sure how Buzz boxes fair with wifi either. Wired connection is preferred regardless.

They're both Android boxes, so they both can sideload apks.

I have a buzztv XPL3000 it seemed great when I got it but couple things bothered me. Doesn't accept m3u's in the built in player like the z7, the guide is slow to load, I have a large 65 inch TV I want more channels to display in the guide than what it shows. I used their app for a while then stopped completely and used 3rd party apps. IMO 3rd party players like TiviMate and Solarplayer have come a long way and offer great functionality.

I know z7 users for the most part love them, so maybe they can speak on how it works for them.

Both do allow you to install APK's.

Since buying my buzz u have used/set up Nvidia Shield and Mibox S's and I must say having Android TV and HD Netflix is really nice. And for the price of the Mibox especially when it's on sale it's a better buy IMHO.

I have both, and I like both for sure. They each have their weaknesses. I like the interface of the Buzz box better. However the MyTV Online app is hands Down the better app. I’ve had issues with both boxes and android app compatibility but my buzz generally get recognized as a tv box rather than a mobile device.
Honestly though, I’d wait for the Z8 and see how that performs as it comes with a new interface that seems to be wholly better overall.

I had both for a year. Just sold my z7+. Buzz is better for me overall. Just plain works. Quick and easy for the family to use. Cleaner and simpler UI. Small and simple remote. Way better since the recent update. I'd probably keep the z7+ if I were single but the buzz is a better family box.

I have used Mag 256 and Buzz, I can tell u nothing beats a IPTV onnly Mag. I have used MyGic and Buzz - kept aside now