I will list my choices and why. Here goes nothing:
Starks/Tullys: Blackfish, was the trillest OG in the game.
Nightswatch: Ed, he says a lot of funny shyt like in 2nd season when he was talking about seeing a man died and how he just kept farting lol.
Lannisters: Cercei, she's ruthless definitely will do anything to stay in power.
Tyrells: Lady Olenna, nickname is Queen of Thorns for a reason can destroy your soul without laying a finger on you lol.
Greyjoys: Euron, the best sea general in the series I'm biased here because the book version is 10x better than the show plus book version has valyrian steel armor :O
Targaryans: tough choice because Danaerys be selling but when she chooses to boss up aka "be a dragon" she's easily in my top 5 for the series.
Martells: Prince Oberyn, was extremely skilled and extremely intelligent he went to the citadel and forged a couple links for his maester chain and then quit because he got bored. His hotheadedness got him killed he had the mountain beat.
Arryns: no valid entry available, we don't know enough about Jon Arryn, and I refuse to nominate his bichazz son lol. Maybe Bronze Yon Royce is suitable replacement.
Baratheons: Robert, possibly the greatest warrior in the series wasn't as talented as bigger names such as Jaime Lannister, Raegar Targaryan, and Barristan Selmy but when he's furious he lives up to his house's words: "Ours Is The Fury" and he will smash them all.
I think I covered all major houses lol.
