dyson are something of a sacred cow I think. I have both. we bought a vax upright on sale and were then given a new dyson. both were the pet hair versions (cant find the model numbers) .
the vax is heavy and loud but the suction is brilliant and so it the brush. I think it gets the dog hair and toddler detritus up better than the dyson.
the dyson however is lighter and much more maneuverable. it is much easier to do the stairs and other awkward places.
so I guess it depends what you want. if your carpeys are really mucky a vax might be your best bet. if they are only moderately dirty then a dyson might suit.