We use the commercial version of Connectwise, but I also use the free version for a couple of PCs.

Teamviewer is probably the best of the free versions, but that is probably why they are trying to crack down on heavy users.

There is also https://www.remoteutilities.com/buy/free.php
Years ago I tried using http://www.ammyy.com/en/ . I accidentally let a random hacker in (you have to accept an invention). He took control of my mouse and claimed to be IT (he wasn't). I uninstalled and never went back.