I've said it on HN before but it bears repeating: If you have a OnePlus, do yourself a favour and put LineageOS on it. It works perfectly on my OP3.
I just asked another commenter who suggested Lineage to talk a little about their experience with it since I just flashed PA onto my 3t this past Friday. I'm going to check it out a bit today. Do you know if it's a simple process to go from PA -> Lineage? A little about me: I am a pretty experience developer but not much of a tinkerer when it comes to phones. This flash to PA is only the third time I've done this wit…
1. Unlock bootloader
2. Install aftermarket recovery (CWM or TWRP)
3. Install new ROM (PA)
Now that you've done 1 and 2 (usually the difficult parts), you really just need to repeat step 3 with a different ROM.Assuming you have TWRP installed, LineageOS has instructions for your specific situation (installing from recovery) at: https://wiki.lineageos.org/devices/oneplus3/install#installi...
If you have CWM or something else, it should be relatively easy to translate the instructions to your specific situation. If you have trouble, you can just start from the beginning of that document for instructions to install TWRP instead.
If you want Google Apps (gmail, etc) installed, you'll need to download that from here: http://opengapps.org/ (ARM64, 7.1) and treat that as your "additional packages" for the purposes of those instructions.