I think I rank the seasons 4,2,3,5,1. Favorite moment of the series is still McNulty crashing his car twice, grabbing breakfast about to pass out at the table, banging that big ty waitress and then seeing his car all ed up and parked crooked outside her apartment in Season 2 I think.
Either that, or when they did that pros ution sting and he was banging two of them when the police bust in.