[ZTE Axon 7 Questions & Answers] Dodgexander:
I was about to make a similar thread myself but saw this one. I have been running custom roms since day one but have been considering returning to stock.

A brief summary of the benefits:

Reasons to go with stock:

Fully functional ZTE camera app with no bugs - This is perhaps more important than you might think, ZTE haven't enabled the Camera 2 API which means its very possible we are going to get the best quality and feature-set by sticking with the stock app. If ZTE haven't released their blobs there could very well be reasons to stick with the default camera app...not only that but I like it. You can install the mod, but there are aspects that will never work and some roms and kernels play more nicely with the mod than others.

Dolby Atmos app. Similar to the camera on stock this would just mean less messing about, you can of course get atmos mods in magisk but whether they work as well as the stock ZTE app I am not sure. The strange thing is I have never had the stock ZTE Axon atmos magisk mod to work on a custom rom, even though I have an Axon!

Reliability, no need to worry about force closes or apps not working, everything pretty much just works. So much less stress if you use your phone as a daily driver.

Ease of use, less features makes the phone easier to use. In some cases even when you are a tinkerer like me its sometimes good to be able to forget about continuously tweaking stuff and digging yourself in to a never ending upgrade cycle.

Oreo, it looks like if you stay stock we will see Oreo sooner than custom roms.

Reasons to go custom:

Substratum, oh boy would I miss this going back to stock. The ZTE theme engine is pants compared and I love the work that goes in to my current premium theme.

Battery life, perhaps with the aid of also a custom kernel there are some very nice roms and kernels being worked on which allow you to fully customise and save battery life.

Features, you can set the phone up exactly as you want too, every small detail can be customised. You can choose exactly which rom you like based on the features you use.

Performance, you can get more performance out of a custom rom with custom kernel and find a nicer balance between battery and performance, whichever suits you.

Fun, its fun to flash different roms and get the flashing bug. You learn a lot and get to join in with a fantastic community where people help each other.

Third option, run a debloated custom rom.

Seems to be more and more popular, as an ex Nexus 5 user I loved Cataclysm rom for this very reason. You keep all the features associated with stock with added performance benefits, fixes and less bloat. There is a downside if you plan on keeping atmos as some stock roms seem to strip it away, but it is a nice compromise between the options above. Usually these roms are more reliable as they are based on stock too. If you want a lean rom that just works, this may suit you!

Its such a hard choice and one I still havent decided on, if I have missed anything please let me know!

Background info and summary:

My first smartphone was a ZTE blade 2 and it was a beast for the money, this phone is tremendous too. My GF owns a pixel and apart from the camera this phone trumps it for value no question...for less than half the price.

I have to say though, I do miss the days of my Nexus 5 and the larger mod community, I realise these days have gone now with google devices but perhaps next time I will opt to go to Oneplus just so I can trust a bit more that there will be less caveats going custom as if there is one complaint I have with ZTE it is their unwillingness to release their source code for the little tiny things like the camera api and atmos.