I keep most of my photos in cloud storage (Google Photos, among several others), but a few of my favorites are kept in the phone's local storage. I have a cheap phone that doesn't have much local storage, and the majority of that consists of system files.
I also prefer to use several cloud storage services, in case a photo goes missing or cannot be accessed.
I use local for my phone - I don't keep important things on my phone. On my PC I use local, Cloud and External Hard Drive... all depends on what the file is. I also do a mirror backup every day to an external hard drive. Each mirror overwrites the previous one.
@Ontheroad Google Photos will, upon request, delete everything locally that is already backed up. It's not so much about privacy for me; it's more about just keeping it organized and clean.