my favourite is probably "Knock, Knock".
i also love "Wild Love", "Julius Caesar", "Red Apple Falls", "Dongs of sevotion". the compilation of b-sides/rarities "Accumulation:none" is also really good...
and i would also recommend the EP "Kicking a couple around", which features the aforementioned wonderful "I Break Horses"...
here is a video for that song:
http://www.youtube.com/watch?v=1g_I_yf2mS0