Not tried any really good ones - I got some Milani ones which were a hell of a lot better than the 8 for £10 set I had, they work well.
Although I will admit I also think those really cheap 4 in 1 rasps are really good, so take my advice with a grain of salt :)
Not sure if they ship over there, but the Italian ones seem to give better bang for the buck than the really good French ones (Ariou & Liogier)
Milani Riffler SetThese
Teranti ones look Ok as well, although not tried them.