Whatever bokeh the GH5 has, the GH4 will have, as well as the GH3, GH2, GH1, Olympus EP-1, and any other 4/3-format camera.
Whatever bokeh the A7SII has, so will any other full-frame camera.
Whatever bokeh either has will change as soon as you change lenses, because bokeh is not really about how out-of-focus the background is. That is simply depth of field. Bokeh was the Japanese trying to find a way to discuss the subtle character of the out-of-focus objects: their shape, outline, etc. Their size is just a factor of depth of field, which is a just a factor of exactly three things: focal length, focus distance, and f-stop. But the bokeh will be different even between two 50mm lenses by different companies on the same camera, or even two 50 mm lenses by the same company but that are different models.
This thread brings a whole new meaning to the phrase circle of confusion.