From my many conversations with other photographers there seems to be two thoughts on how to protect the front lens element. There are those that believe filters offer the best protection, while others claim filters reduce image quality making lens hoods the best option.

Typically photographers choose either a UV haze or skylight filter for their lenses. They both reduce UV haze; however the skylight has a little pink tint to warm up images. Warming up images can be controlled by the camera or done in software like Photoshop giving the photographer greater control of the final result. As such, UV filters are recommended and more commonly used than skylight filters. The front lens element doesn't need to be cleaned very often and has less of a chance of being scratched when using a protective filter. Plus if the lens front gets bumped, a damaged filter is easy to remove while continuing to shoot. Compared to an expensive lens, most would prefer to replace a filter.

However adding a filter to the front of the lens can affect image quality. Using good quality filters normally won't make any noticeable difference. Image quality tends to decrease with stacking filters, especially on wide angle lenses where vignetting is a concern. The simple solution would be to remove your protective filter in a windless dust free area when using other filters. While not all image quality issues can be fixed in post, Photoshop does provide a simple solution to fixing vignetting issues.

Hoods on the other hand, don't cause the same image quality issues filter do. By preventing flaring, image quality is more than likely to improve. Properly designed hoods are also meant to stay out of the frame, eliminating the chance of vignetting. Plus unless something is small enough and coming straight on, the hood could block things from hitting the front lens element.

Not all hoods are created the same. For telephoto lenses they are tubular, while wide angle lens hoods are petal shaped. Even the tubular hoods vary in depth. The amount of protection they offer from stray objects varies greatly by the construction of the hood itself. Additionally no hood will protect the front lens element from gritty dust blown by the wind. While hoods provide some level of protection, they are better used for shielding the lens from stray light.

Both filters and hoods offer some protection to the front lens element. Lens hoods will potentially improve image quality, but offer less in the lines of protection. Alternatively filters offer more protection, but have the potential to reduce image quality. Even so, UV filters are commonly recommended by lens manufactures to protect the front lens element.