In my experience, Proton gets better performance than native, and often with fewer issues.
In particular, dxvk being on by default alone is a huge deal.
Lower overhead and less cruft in the OS.
Uninstalling a game leaves basically nothing behind, no add/remove programs nonsense.
I'm looking forward to trying to get a good setup on FreeBSD (Linux steam, native proton) at some point, because I'm not a fan of Linux as an OS at this point. Doesn't feel that different to Windows in design, just less crap.
I'm very high.