There is no best manual, and the manual should be chosen with the specific shooting dicipline in mind . Each manual offers a different benefit to the handloader. I think someone starting out should have a minimum of 3 manuals. Which manuals you choose does not really matter, but folks starting out seem to get good value from the Lyman and Hornady manuals. The third manual would sort of be a toss up between the Sierra manual and the Nosler manual. Although the data is beginning to get a little dated, Ken Waters' Pet Loads is a valuable reference, and should probably be considered as the 4th manual.
It is also important to make sure the manuals you choose has data, which will be of benefit to you. With so many new cartridges, bullets and powders being brought out, and so many old cartridges being resurrected, the manuals don't seem to be able to keep up. A little research might be in order.