They're all mediocre, but start at the first one. The books are denser than the show, and the show corrects a lot of dumb shit that's in the books, like all of the main characters being pre-pubescent godlings who are somehow smarter, and more tactically and technically proficient than the grizzled battle-hardened 60 year old war vets. Yes, Stark 10 year olds, show me how to fight wars. I've only been doing this for 40 years. The books are retarded.