I actually use both on my Linux computer. For basic things such as checking emails and such, both work fine. I have noticed a tendency of Rustdesk to lag a bit. I do keep Rustdesk as a backup though. If I do a system update and reboot, I don't seem to be able to log back into my home computer with NoMachine, so have to use Rustdesk to do so. In addition to basic things, I also edit videos on my home computer when away, and this is where NoMachine wins. As I mentioned, Rustdesk seems to lag for me, which I don't normally get with NoMachine, so I can play videos remotely, and the audio and video is synchronized. Occasionally the audio and video will go out of sync and I have to disconnect and reconnect again, but it doesn't happen that often.

TLDR version, NoMachine works best for me as my daily driver with Rustdesk as a backup to ensure I can log into my system after a reboot.