I love the look and polish of Campy, but I switched to Shimano Dura-Ace years ago and haven't looked back. It is in my opinion the best high end groupset for the money. Easy to service, easy to maintain, easy to get parts. The Dura-Ace cassette is lighter than Ultegra and 105, does it really matter - to me yes it does. I have high end carbon whees and bike so I want all weight advantages I can get. This cassette with dura-ace chain and derailleur is quick, crisp shifting!
Shimano has always come out with great products and always cutting edge in technology. This cassette by far is the best cassette i've ever used, so light and gotta love that 30 gear...