Panasonic GH5S vs GH5 - The Best 4K Camera

Which one is the best mirrorless camera for 4K video - the low light GH5S or the tried and trusted GH5?

GH5s In-depth look on CVP: https://www.youtube.com/watch?v=VdCPrEBs-6E&t=1s

GH5s Body Only: https://cvp.com/product/panasonic_gh5s_body