After trying the Hydro 5 a couple of days ago, I think I’ve used pretty much all of the modern cartridge systems and can now confidently say that the Atra/Contour/Ultra is my favourite.
I also feel confident in saying that actually Gillette, Schick/Wilkinson, Personna, Dorco, Bic they're all very good (because they have to be in such a competitive market).
With good prep and technique you just can’t go wrong with any of the major brands