If you include all the HORSE games, then SUPER SYSTEM is a good book to have read. It is the biggest of all poker books, maybe not a book you want to lug around the rest of your life.. It is also basically old style, but the fundamentals in it are rich with info. I have thought many times thru many books, that all those authors of the other books assume you have been thru SS. And they then build on that.
For tourneys, Harrington is still a great book for fundamentals.
Each of those books is never done teaching. I have been thru SS 3 times, and HOH at least 5 times, and I swear each time is like I never opened them before.
I have a book from Susie Isaacs, something like 1000 tips. It also covers all the HORSE games. It's value is that it reminds me of stuff I already know. Stuff I have somehow repressed for weeks and need to get reminded of. I have been thru it 3-5 times also. Probably time to break that one out and stick it in the bathroom reading rack again.
Most poker books are good in the bathroom reading racks. They tend to have short sections covering specific topics, or maybe hands with some sort of specific info. If you are constipated, you will learn poker faster this way!