Depends on the situation. I'm a patrol sergeant, when I'm on the street I don't carry any hearing protection.
When shooting at work, it's plugs and generic-range-issue muffs that everybody else wears.
I've only recently started instructing (part-time) at work, and then it's my own non-electronic muffs and loosely inserted plugs. A couple of the full-time instructors use their own electronic muffs, I haven't had a chance to borrow theirs yet.
I shoot USPSA frequently...at outside matches generally just muffs.
It works for me, but I'm always looking for something better.