Most overrated – probably Littlefinger. Not that he’s bad, just that he’s not the godlike Joker-in-Dark-Knight genius everyone thinks he is. He’s sloppy, egotistical, and weirdly antagonizes people with power over him. He’s going to lose everything because he’s too busy monologuing to take Sansa seriously.
Most underrated – Eddard Stark. Not that he’s great, but when he actually makes use of the powers of the Hand of the King, he gets Tywin Lannister to openly commit treason. If Robert hadn’t died precisely when GRRM needed him to, the Lannisters would have been politically isolated and the War of Five Kings would never have happened.
How did Tywin openly commit treason?
He attacked Beric Dondarrion who was carrying the king’s banner. That’s treason and rebellion.