I don't think I have a preferred house over another; it's the actions of it's current members that would make one seem more or less favourable over another. Slytherin gets a bad rap thanks to Voldemort and his followers (And I guess, it's founder) but some of the greatest witches and wizards came from Slytherin house. Merlin, for one! 

Oh, and if anyone is torn between putting their character in a certain house, I'll likely be allowing multiple characters. :D