You just can't go wrong with any of these cameras, just need to work on the weakness of each one, the most important thing is to keep a nice balance between image and sound, you need to get your light right, your sound right, nice B-roll and nice interviews shots, preferably with two cameras.
I'm pretty sure that you can get a lovely image from any of these cameras, I used an Om-Em5 like 4 years ago (lovely camera btw) for a pilot show and worked perfectly fine, now I'm using two GH5 and a Sony a7s with 4k video recorder, mostly when I need a lovely full-frame look or a low lighting situation, but coming from the GH1 and now the GH5 and after using differents cameras through all these years, I can't leave keeping recommending the GH5/GH4, not only gives an image that works for almost all 90% of our video productions but something that for me is essential in the field, and is reliability, it works all the time no matter the situation, I just can count with the Lumixes, are very versatile cameras, well built, nice size, excellent options for video and audio recording.
Photo image quality of the GH5 and the OM-EM1 MKII are very similar, maybe the autofocus tracking system on the Oly could be more reliable.
Enjoy your production.