Depends what you want to film really.
The footage from the backpack/harness mounts can be pretty cool if you don't need to see your face. I've seen lots of good boosting shots from these as you get a nice perspective of height.
You can get really nice footage from a selfie stick held with the back hand too. The advantage of the stick is you can move it to show your face if needed. Can get some good spray photos from this but you need to be good enough to fly one handed. I think this is a really nice example of the type of footage you can get:
Then the pros often film with mouth mounts. The main advantage being that a lot of the camera shake is reduced but you are a bit limited to having to hold out the camera.