There are two distinct camps on the use of protective filters, and they will defend their choice with almost religious fervor.
On the one side are those who would never put a cheap piece of glass in front of a high quality lens, and they are right.
On the other side are those who would never walk out of the house without a filter over that expensive lens, and they are right.
Filters (at least non-multicoated ones) have been shown to degrade the image, sometimes very noticeably. Scratches do the same.
I decided to not use a filter (except a polarizer, and then a multi-coated one) in front of my lenses so I could get the best image quality possible. I realize that some fine day I may get a nice scratch or worse on my lens and I accept that risk as part of the quest for better images. I always use a lens hood so at least the lens is somewhat protected.
What's your choice?
boB