Mine are either Targaryen (subtract Dany) or Lannisters. I love the sigil, colours and characters of house Lannister (yes, even Cersei). Jaime is my favourite male show character, and Tyrion is just really good looking in the show (he's a total badass, too.)
Targaryens are sick because of their history. They're the most based family in Westeros, if you ask me. Red and black are also very cool colours for a house. I also really like Rhaegar and his son, Aegon, [spoiler]if Young Griff actually turns out to be him.[/spoiler]
So, Flood, what's your favourite House and why?