Any advice on a 4k camera with good follow focus?
You need to post more details. Are you looking for suggestions? There are many 4k cameras with good follow focuses. Also, the focus is only going to be as good as the person pulling it. Are you shooting documentary? What about the Amira? Are you shooting in low-light? What about the F65? Are you shooting in bright light? What about Alexa? Are you on a supreme low-budget? What about the GH5?