[AT&T LG G3] CaseyCor:
I have used most every G3 ROM there is, haha. Candy5, CyanideL, previous versions of RR, Cm12 proper, etc.. Each ROM has its own issues, and some of those issues will be unique to your device. I'm not sure why that is, but it seems to be true. I had much better luck with custom ROMs on my HTC One M8 than the G3.

These issues I'm referring too are mostly minor annoyances that are worthy trade-offs when considering the other benefits such as performance, battery life, and customization. Examples of some of these issues include specific apps crashing (Flipboard has been unusable for me on every custom ROM since Lollipop was released, including this ROM), black screens in Chrome when multitasking away and returning to the app, black screens after ending phone calls, LiveDisplay not working, Expanded Desktop freezing (navigation bar won't unhide, have to pull down notification shade to get it to show up).

My suggestion for you is to give this ROM a try, and keep notes about the performance. If you make a Nandroid backup of your current system, which is always suggested, you can always go back without losing your storage (pictures/movies and the like). Also, back up your apps with Titanium Backup, and save the backups on an external SD card if possible. Flashing and setting up a new ROM is a quick and short process.

If you find you like the AOSP/CM structure over the stock LG interface , but have issues with this particular ROM, give another custom ROM a try. There are unofficial builds of CM13 (Marshmallow) available, and several Lollipop ROMS, which I listed above and can be found in this very forum.

Outside of this ROM, I've had the best luck with CyanideL, lollipop versions of this ROM (RR), and Orion LP. Before switching to this ROM, I ran the dev build of CyanideL for a few months. It's pretty solid, and has some unique features. It can be found on the first post of the CyanideL thread in this forum.

Try this ROM out for a few days, and if you have any issues, you could either go back to stock or try out another custom ROM. I'm having good luck with this ROM so far, but I won't comment on stability until more time has passed. A day and a half isn't long enough to make a judgement one way or the other.

I did find two bugs with this ROM today. Attempting to launch Netflix completely crashed my phone, forcing a battery pull. I've read about this issue with other ROMs before, but never had it happen. Also, rebooting the phone via a prompt in an app causes a black screen of death. I've had this happen when using L Speed to reboot, as well as the Xposed app and GSam Battery Monitor. Rebooting the normal way (holding down the power button, tapping on reboot) has yet to cause a black screen of death though. So far, it's only happened when executing a reboot through a 3rd party app.

BSoD have plagued me since I got this phone, across all of the ROMs I've used. So far, this ROM hasn't been as bad. On other ROMs, it would happen when simply rebooting from the system power menu, or even randomly while using the device. Taking my phone out of the case, removing the back and pulling the battery isn't a fun thing to do when out and about. Hopefully this ROM continues to run BSoD free (outside of the above issue).