I have several reloading books, but the two that I reference the most are the Hornady and Speer manuals. I just picked up the latest Speer manual and am quite impressed with it. I use a lot of Hornady bullets, so naturally I start with the Hornady manual when I am working up loads with their bullets. I don't shoot as many Speer bullets, but I do shoot a lot of plated bullets, and the Speer TMJ bullets are thick plated, and I have found the load data for the TMJ bullets to work well for Xtreme and RMR plated bullets, other than the fact I have to determine the OAL using the plunk test. Speer does have their load data online now.
And I also have the pertinent load data from the powder manufacturers either in their (usually) free handouts, or I have the data printed out.
I also have the Ken Waters "Pet Loads" book. It is pricey, but invaluable IMHO. The data is dated (some of the powders listed are no longer available) but it is great information nonetheless.
The Lee manual has lots of data, but none of it is their original data, it is simply a collection of data that is available online from the powder manufacturers. While it is handy to have the data in one place, it leaves out certain pertinent information, like barrel length, that is available if you go to the powder manufacturer's websites. The loading tutorial in the front is not bad, but it is certainly a sales pitch for Lee products.
I think one of the best independent sources of load data is from Lyman. Their loading tutorial is also excellent. This was the first load manual I bought and I am glad I started with that one.