Oddbean new post about login | logout how do you evaluate a relay operator? is he judgmental? is she acting based on personal views? is she spiteful ? is he fat?
All of them. + How fast can he run a REQ call :)
I would say privacy is high on the list. Maybe a bit like VPNs. Very few relays or devs call out privacy, right now -- I can think of about 2 -- but in future it could be something that users value.