Well, Hawks are also about 50% faster than ravens and crows. Owls probably are too, but I don't have their stats handy.
But frankly, D&D is about having fun, and a crow is just simply more fun than a hawk. Therefore the crow/raven wins the best familiar award hands down.

Seriously, there have been times when I'll send Xilinx (my familiar) off to check something out and he'll come back with some totally random information that has been filtered through the eyes of a marginally intelligent bird, and the party will spend a good fifteen minutes RPing with the damn bird. How many other familiars are a dependable source of roleplaying encounters?
Oh, and about the Crow/Raven being associated with witchcraft by the common folk, that's one of the reasons why I chose it.

My character is a halfling necromancer, and really looks more like an evil feral halfling shaman anyway. The mangy black bird following him around only completes the look.