I’m looking for remote access services that work on Windows macOS and Linux

Hi! I’m looking for remote access tools that work well on Windows, macOS and Linux. Ideally, they’d be reliable, easy to set up and preferably free. File transfer support would be a plus but my main focus is on cross-platform compatibility and ease of use.
I know there are plenty of options available but I’d really appreciate hearing about your personal experiences with any of them.
Thanks in advance!