Personally I'd say:
- If you want ProRes, buy and use iShowU Instant Advanced (macOS only);
- If you want to use OBS, then set ffmpeg to encode in DNxHR.
I've been screen recording in OBS to DNxHR HQ for some months and it works very well.
iShowU Instant is easier for a new user to get going though, and if you really want ProRes, it's definitely the best option - despite the VFR. It also has easy-to-use and good looking keyboard and mouse reporting, You can set all that up in OBS as well, but it requires more work and investigation on the part of the user.
One potentially big downside of OBS recording on macOS is that there's no built in way to record the desktop audio. That's another benefit of iShowU Instant: it includes a special driver for recording your desktop audio as you screen record.
Personally I enable desktop audio recording in OBS using
Loopback, a very powerful and cool audio routing app - but it's also rather expensive if all you want it for is desktop audio recording ($99 + tax).
iShowU's desktop recording facility is quite useful. In fact, in the past
guides to OBS recording on macOS actually recommended downloading the iShowU desktop audio recording driver, so you could get desktop audio recorded in OBS as well. But that driver only works up to Catalina.
For Big Sur and later, the makers of iShowU released a separate paid-for app called
SWB Audio App. Or if you buy iShowU Instant it comes with the same audio driver, which I think will still work in OBS as well.
So to record desktop audio in OBS on Big Sur or later, you need to either buy SWB Audio App ($12/year), iShowU Instant ($39), or Loopback.