For one, OpenScreen supports Linux, whereas Cap doesn't. I appreciate it's small minority that appeals to, it's just that I'm in it.

This one is free even for commercial usage.

so is cap if one has the will to build from source, no? https://github.com/CapSoftware/Cap/blob/main/LICENSE

I've also found https://framecapture.pro to be a super good free alternative to Screen Studio. It's got... literally everything...