A good filter is generally going to cost as much as repairing the front element -- and even the best filters are still going to degrade image quality (even if imperceptibly in ideal lighting conditions).
A lens hood, on the other hand, is always going to improve image quality, plus it offers superior protection to all the most common dangers lenses face.
There are only two scenarios where a filter makes sense for protection. The first is for weather sealing for lenses that require it (and, obviously, only in adverse weather conditions). The second is where you yourself require eye protection: rodeos where the horses are kicking gravel at your face, seaside where the waves are crashing on your head, that sort of thing.
Of course, polarizing and neutral density filters are a completely different story.