Here is an interesting shootout report of the above:-
http://financenews.sina.com/digi/dc/2008-11-05/08562557433.shtml
(Text in Traditional Chinese, you can read the Babelfish English Translation Here)
Page 1 to 2 are the Introduction parts for the UV "filters" (actually most of us use them as "protectors", I would say). Page 3 talks about the testing methodologies. Page 4 to 7 are the detailed descriptions on different make/models of the UV protectors under test. Page 8 to 12 are about the testing results obtained of which Page 8 to 11 is about the optical performance aspects whilst Page 12 is about the immunity on dirt and the easiness of cleaning of different filters. Finally, Page 13 and 14 are Summary and Conclusions, Remarks and Comments.
Well, amongst all those tested UV protector make/models, I own and used/use almost most of them (I do not use filters that doesn't have coatings (MC)). Brand wise, the Canon and Leica protectors are the only two which I have purchased any of their protectors so far. But I do have other renowned brands like Heliopan and Contax etc., which I think are also quite good.
As for the test results and conclusions contained in this report, I think they match well and coincide mostly with my personal experiences, over years. So, this report is valuable to read and I consider it to be quite good and is highly recommended, especially when they put and present it in a more scientific way.