[Xiaomi Mi 5 Questions & Answers] JRC1995:
Personally, my favorite among the ones I have used is Resurrection Remix. I am a fan of the stock-ish android looks. It's based on LineageOS, have VoLTE support and it has loads of interesting customizations. Other than that it also performed well, and didn't notice any drastic battery drain compared to other roms (though I didn't actually used the rom for more than half a day or so). Still I played a lot with the rom, it appeared pretty stable to me. (NOTE: I used "RR-N-v5.8.2-20170401-gemini-Official" version. Don't know if latest versions have some new bugs or issues) and of course it's bloatfree ( at least compared to MIUI).

But there are some reasons for which I am not actually using RR.

1) Camera. RR comes with snapdragon camera with stock. The camera performance is good enough (normal camera pictures can be on par with MIUI or may be even slightly better (never actually tested properly))

But the HDR is not as good. It works kind of but makes pictures look a bit unrealistic...things a bit too bright. I also tried many 3rd party cameras but none had the HDR as good or as fast as in miui.

Also, it seemed like no camera app was perfect in the rom.

Almost all third party apps have certain problems like:

i) Macro Focusing\ Focusing some near objects (it worked for some objects but didn't for some others). (I was especially having problem in focusing some decorative fake plants)

ii) Focusing while taking pictures with flash. It wasn't working properly.

Stock Camera had no such problems in those regards. But it had some other share of problems:

i) Video Recording audio too low (works pretty well however in some 3rd party camera apps like footej camera. I suppose snapdragon camera does some heavy noise cancellation or something)

ii) Preview pictures locked in portrait. (not really an issue, but a bit annoying)

Also the overall interface feels a bit slow and clunky.

And you might need some other 3rd party camera app for better manual controls. So to get the most out of the camera I had to keep three-four different camera apps with different pros and cons for different situation and also had to compromise auto-HDR (and even just HDR)

2) Snapdragon Camera in RR was still alright to me, even if I prefered miui stock camera (which even if not perfect had almost all the options I needed along with good performance). I still could have stayed but there was another major thing that was bugging me. Super Hexagon (a game) had no soundtracks. I have some attachment with that game, and also the soundtracks are a major part of that game. I found out that the native android player had problem playing ogg files (which were the files super hexagon runs). VLC player seemed to be capable of running ogg files but most other music players were having problems. It might be some android 7.1.1 issue and it seemed to be present on some other phones too (as I found from google search). There was actually a roundabout way I could run the game with the soundtrack but I wasn't too willing to entertain the idea of using the roundabout way each and every time I wanted to play the game.

Those are the two main issues that prevented me from truly being comfortable with RR; all other things I liked better than miui. Even some games seemed to perform better. Still it was a good rom; if you are alright with the camera and don't care about playing super hexagon, the rom should be worth a try.

Also note I tried a lot others 7.1.1 non-miui custom roms from XDA, all of them seemed to have these similar issues.

I switched out of the official global rom after I found out I couldn't get some 3rd party widgets to work properly after reboot. After that I flashed Xiaomi.eu and never looked back to the 'official roms' anymore. Xiaomi.eu seems to be updated as quickly as the official...it's also based on the china rom (which is considered to be more supported and stable) and it's relatively much more bloatfree...it pretty much wins against the official rom in all respects IMO. I tried some newer (but not currently the latest) dev versions and the last stable version of xiaomi.eu. Those were satisfactory at the beginning but for the sake of testing; I tried other roms (because I am not a big fan of miui look) and then after finding these issues I switched back to Xiaomi.eu...but I started having some other problems:

1) Google Play store downloads were 'Waiting for wifi" indefinitely. It was all working perfectly sometime ago. But may be google changed something idk, and there was those problem...however the problem also seemed to be more or less specific to miui. Lots of fixes were posted in discussion forums...tried a lot of things....couldn't fix it totally unless I kept it downgraded to factory version and disabled some receiver making it unable to automatically update. It may be fixed now but IDK.

2) Still, downgraded google play was fine. But it felt that some of the heavy games were not performing as well as lineage OS and similar roms. GTA SA's graphics looked glitchy...even if the performance was ok. Bully wasn't performing that good in max settings (though it never performed 'perfectly' in any of the roms I tried. I guess I overestimated sd 820)

3) Notifications are not as good. In android 7.1.1 when you pull down notification of google play downloading an app, you can get pause, cancel options at the notification directly...not present in miui. That's ok...but what's kind of annoying is that Shuttle Plus Music Player was just an icon in the notification ...without the album art and the pause\play buttons (which is how it should have been). It looks like MIUI is not very friendly with 3rd party apps. Also another strange bug is existing in miui since quite a long time (if you use a theme or any apps that shows the time including the alarm time, it shows an arbitrary time if alarm is not set.

So...I again switched to android 7.1.1 custom roms but still wasn't satisfied. I wanted to try android 6 based xiaomi.eu rom; actually I did try quite a many times but ended up soft bricking always. In the end I managed to get into Last Xiaomi.eu Android 6.0 stable rom (v 8.1.6.0) by fast using mi flash tool to fastboot flash an old miui 7 rom then updating my way up to 8.1.6.0

And currently I am in that rom. I have the most satisfactory miui experience in this rom (still I think I prefer RR for design and interface). Since I am rooted I edited build props to enable camera 2 api which wasn't enabled by default. The interface is pretty much the same as android 7 based miui 8 (you won't notice any difference). The only thing I miss is the notification toggle of battery saver...(battery saver mode is present and can be enabled from security app but the notification toggle isn't present but it's no real issue). There are some other minor bugs like miui theme wallpapers (from theme apps or settings) can't be changed if using a 3rd party launcher but not any big deal for me. Surprisingly I found that Shuttle + music player's notification is properly showing album art and pause\play buttons.......and Games were working better too, I think..GTA SA was running pretty well (though I think LOS or other AOSP roms were better) too. And Super Hexagon worked. Camera was fine. And with android 6 some more additional games were compatible (the games are now unsupported (and abandoned) and crashes on nougat). Also, you can use Xposed and other things in MM). So for all these reasons I think I will be settling at 8.1.6.0 for a while and will be ignoring the new versions for quite some time.

Now it's your choice what you can compromise, what's your priority and such....then make your decision.

May be try both.

If you are going to try more than one rom, I will recommend you to try 8.1.6.0 the last. Switching between Nougat Based Xiaomi.eu and AOSP roms is easy with twrp recovery. Switching to Marshmallow Xiaomi.eu from Nougat and back can relatively a bit twisted (still should be a lot simpler than what you went through until now).