UPDATE: Camerastuffreview tested the Panasonic too:
If you have large hands, photograph often in poor conditions or prefer lenses with a long focal length, then the Panasonic GX8 might be a more suitable candidate. If you want to use the camera primarily for video, then the Panasonic GH4 is a more obvious choice. In all other cases: It is a pleasure to work with this handy camera. The AF of the Panasonic GX80 is really lightning fast. 4K photo offers the option of recording action at 30 frames per second and saving the best picture in the camera. Go ahead and argue with them, the photographers who choose a Panasonic GX80 over a Leica or a Canon.