We've been using the Panasonic GH5 since they first came out. No doubt about it, for the money they're great cameras in many respects.
But I wouldn't buy another one, apart from for one specific purpose. Why? Because of the Blackmagic Pocket Cinema Camera 4K.
Both devices use similar sensors (possibly even the same sensor, from what I've read), both are a broadly similar form factor, and they're priced towards a similar market.
I'm here to tell you that the BMPCC4K is a better camera for videographers, in just about every way.
First, the GH5. It's a nice, solidly-built little camera, and the footage that comes out of it gives good results without much fiddling - nice, vibrant colours and sharp images.
But it's very much a compromise. This is a mirrorless stills camera which happens to be quite good at video. In the traditional Japanese style, it's festooned with buttons and switches.
Two rotary selectors on the top give access to 16 different options. There are three finger/thumbwheels, which you might want to map to gain, aperture and shutter speed - but you have to remember which one is which, and for video you don't want to accidentally change your shutter speed.
There are no fewer than 11 small pushbuttons scattered haphazardly, a 3-way rotary focus mode selector, a joystick and a touchscreen. Some of these are too easy to catch with a finger unexpectedly. I'm all for having hardware buttons to access key features, but there's little rhyme or reason to the layout and default uses, which means invariably you're peering at the buttons trying to work out which one does what.
Then you get into the menu system. My god. It can take weeks to track down a simple setting. 90% of the settings are irrelevant for filmmakers. Several times I've enabled things on the OSD and it's taken a whole lot of effort to work out how to turn them off again.
Remember how feature phones were prior to the launch of the iPhone? Endless, cryptic configuration screens and submenus, most of which you never needed, but which completely obscured the stuff you were looking for? This is the exact design philosophy for the GH5 - pack in as much as possible, making the device virtually unusable in the process.
That said, there are a few useful bits and pieces. In particular, the automatic focus pulling has been really useful on a few occasions, if you can remember how to find it in the menus.
The Panasonic's small 75mm touchscreen is too small for everything it tries to display; trying to tap an on-screen option with normal size fingers is hit and miss, so you end up using the joystick, which works well for some things and poorly for others.
In many ways, the BMPCC4K is the polar opposite to the GH5 in terms of usability. I counted 13 buttons, but unlike the GH5, they're layed out in a natural, clean way such that everything's immediately to hand. In particular, ISO, shutter speed and white balance are on the top just where you can reach them easily but won't select them accidentally.
Behind these, 3 custom buttons can be used as you wish; I configure mine to enable / disable zebras, focus peaking and a LUT. By contrast, trying to find these 3 features in the GH5's menus takes me several minutes each time. I could map them to buttons on the GH5, but the buttons are all over the place, and mostly needed for dedicated functions in any case.
The far larger 125mm touchscreen is clear, bright and uncluttered. Rather than following the GH5's approach of making the display look like a 12 year old's Myspace page, Blackmagic appear to have actually employed the services of a user interface designer. All key information is clear and easily accessible, and the menus give you exactly what you need within a couple of screen presses.
The default output from the BMPCC4K seems slightly softer than the GH5, and the blues are markedly different in hue, but nonetheless the pictures are beautiful, even if you don't fiddle with any colour apart from setting the correct white balance. Blackmagic give you log shooting for free with the camera's Film dynamic range, as opposed to Panasonic charging extra for a V-Log license on the GH5.
Compared to the metal GH5, the plastic BMPCC4K body feels less premium and it would benefit from a bit more heft. It also has far poorer battery life. However, it does come with an AC adapter, whereas to power the GH5 externally you'll need to use dummy batteries, which are a truly mediocre way to power a camera.
The GH5 comes with In-Body Image Stabilisation. It works well. The BMPCC4K doesn't. If this is important to you, well, there you go.
We use gimbals (mostly DJI Ronin-S) a lot in filming. The GH5 balances well on the Ronin-S, and the focus wheel works straight out the box, as does external record triggering. However, with an external monitor/recorder, the GH5 annoyingly will output only external clean feed when the monitor is plugged in (no on-screen display) - so you lose your menus and aperture display! This is infuriating, particularly as it wasn't an issue with earlier combinations of the GH5 and Ronin firmware.
Recently we've starting getting more use out of the BMPCC4K on the Ronin-S. It's harder to balance, but you can still get great results.
Finally, the BMPCC4K records directly to ProRes or Blackmagic RAW. Why the Panasonic doesn't is beyond me, as it means every bit of footage that it produces has to be transcoded for editing.
The Blackmagic Pocket Cinema Camera 4K is a device designed and built by filmmakers, for filmmakers. It's a camera you'll look forward to using, day in, day out, and it'll work with you to create amazing results. It's a classic.
The GH5 is designed and built by engineers, for engineers. It's capable of great visual results, but you'll have to work hard to use all the advanced functionality it packs in, and at times it'll feel like the camera's deliberately fighting you at every stage.
That said, I still like having a GH5 to hand, purely because of the IBIS and gimbal mounting convenience, which are both missing from the BMPCC4K. However, when using the GH5 with a gimbal, I'll always be using an external recorder/monitor alongside it, for ProRes recording and so I can actually see what I'm shooting.