I used to use a UV filter, but don't use it any more. I bought them initially because I didn't know anything and that's what I was told to do.
After reading and seeing others' views on why you're better off without it, I changed my mind and removed them.
I do use a CPL filter at times but obviously that doesn't stay on the lens as it serves a purpose in certain situations and is then removed.
I also use a ND filter for long exposures when I feel the situation calls for it, but again, not something you can leave on the lens.