season 4 for me.. the narrative showing how the kids grow up into the game and the start of the new set of characters replacing the old ones - michael/omar and dukwon/bubs in particular.
s4 also was the start of a real examination of how fucked up the whole system and a move away from a focus on the drug war - which felt to me more like a backdrop and narrative drive in s4 and s5 than in the earlier ones.. a really good demonstration of how fucked up both systems of election and appointment are.
s4 affected me emotionally in a way that none of the others did, becuase it showed how the system isn't going to help anyone - the only characters who ended up in a better place did so becuase someone essentially came and saved them - caulfield and wee bays kid; bubs and himself plus wayne (?); mcnutty and brodie..
in terms of characters, fuck me.. the worst of the main characters in the wire is better than most characters in most tv things.. I voted for bubs becuase I definately got most emotionaly invovled with him.. omar is definately the coolest character though bunk, mcnulty, freamon, caulfield, michael and dukwon are well up there as well..