System data and other is taking up all my iPhone space on my phone.

Honestly I would say just backup, wipe and restore. My 64GB 8 was showing almost half the storage taken up by iOS (on the bar graphic; only ~8 at the bottom of the list) and ~18GB on system data. I searched for solutions but nothing worked. I was so reluctant to try the 'nuclear option' but it's easy and effective. Now down to 13GB total used and everything else is just as it was. Didn't even need to re-log into my apps. Good luck!