Harrington on Hold 'em
is pretty much the bible on TAG tournament play, well worth a read.
I got a lot out of Killer Poker - No Limit
by Vorhaus. It's very good for analysing your own game and making improvements, regardless of the level you're at, and it applies almost equally to cash games and tournaments.
Phil Gordon's Little Green Book
and Little Blue Book
are solid reads if you really want to get back to basics. They're very much basic / beginner texts though.
If you play live a copy of Read 'em and Reap
by Joe Navarro can't hurt either - squillion times better than Caro if you want to learn about tells
in casino NLHE games.
As for Super System
(one or two - the NLHE section is pretty much the same in both), if all you're playing is NLHE I wouldn't bother. Yes it still has some useful info, but pretty much every important point on no limit is covered in the Harrington and Vorhaus titles mentioned above. I'd only shell out for it ahead of other books if you're looking for something that will help improve your stud and lowball games as well.