I had tried both the Nikon and the B+W ones. However, I feel that the B+W one have much thicker coating and less prone to kena water-mark. The Nikon one smuge very easily.
Both makes are good filters but I perfer the B+W ones.
Actually I think there is another "brand" that might be worthy of our attention.
It has UV filters with different "strengths". Look at sunglasses, with its different UV protection. Sometimes a " weak" filter does nothing at all (except to protect the front element), especially at high elevations
isn't the 'strength' suppose to be 1.0x 1.1x etc... UV filters are 1.0x, skylight filters are 1.1x and so on & so forth... so if you need something more 'colorful' can get a skylight filter or FLW, etc
My technical knowledge on UV filters is not that great, but let me try.
Visible light range fromt the longest (red) to the shortest (violet- at 400 nanometer). Anything shorter than 400 nm is called ultraviolet.
Color films have three layers, sensitive to red, green and blue. Blue also responds to ultraviolet. Films are not sensitive to infra-red and do not need infrared filters (but I was told that digital sensors are infra-red sensitive, and infra-red filters are "built-in")
For most of our shooting, the UV light is low and does not affect color. When one ascends higher to the mountains, the amount of UV light increases, and can cast a blue coloration to pictures. Hence the need for UV filters. Like UV glasses, there are glass with different strengths of UV blocking properties. Whether it really make a real difference is another. It is also true that to correct the potential blue cast, one can use a skylight filter.
But all this is very theoretical. There are other factors that can cause a color cost, including vapors.
So at the end of it, I think the most important use for a UV filter is front element protection! Unless you are a purist, of course!