At best, a quality UV filter will not degrade your lens image quality, but it won't improve it either, unless you are at 3000 m (10,000 ft) or higher.
It takes a bit of work to scratch a front lens element. However, if you have a habit of abusing your camera gear, consistantly use poor camera handeling habits, or wipe the lens objective with a contaminated cloth it certainly becomes more likely to happen.
UV filters are not lenses. They are flat, thin pieces of glass that are much easier to break than is the lens front element, and tend to get broken by forces that push the broken shards back against the lens objective it was supposed to 'protect'.
UV filters add an air gap to the lens which promotes lens flare when the lens is pointed at/near a bright light source. The added air gap also tends to reduce image contrast.
Using a lens hood offers a measure of scratch and impact protection, does not introduce an added air gap, actually reduces lens flare, and increases image contrast.
In short a lens hood offers lens scratch protection and improves image quality.