I like them both. Super System covers every type of poker. If you are just interested in NL Hold 'em, there are only a few chapters that apply, which you can probably read through in an hour. Harrington's books are all good, and I recommend read all three volumes. The workbook (vol 3) is a really good place to test your thinking.
I also highly recommend read Psychology of Poker, which is very different than the ones you mention. But it will give you a way to think about how/why you play, and how/why others play and how to adjust accordingly.
My favorite quote from that book is "Expert players refuse to play a hand without an edge (hole cards, position, etc)".