I don't think there's a best manual. I try to keep my library current, though this can be costly. IMHO, you should have as many sources of information as you can afford, and I think 3 is a prudent minimum. If you have a Nosler, Lyman, and the Sierra book, you will have 3 reliable sources of information, which each approach their data from a slightly different directions. Nosler provides the minimum-maximum load data with the corresponding velocity, along with the load density. Lyman provides the minimum-maximum load data with the corresponding velocity and the corresponding pressure (which should only be used as a point of comparison, not as a suggestion that more is better) and provides some load data for cast bullets. Sierra by contrast lists velocities with the corresponding load load data, an interesting departure from the others, which is why I put it ahead of say the Speer manual. I've found so many mistakes in the Hornady manual that I always weigh its data against other sources. I liked the older #3 Barnes manual, but #4 contains much less data per cartridge than most other manuals. Still, if you intend to use lots of their bullets, it doesn't hurt to have their manual, ditto Berger, Swift, and Lapua/VV. I like the A-Square manual for the information related to terminal ballistics, and for the data pertinent to "African cartridges". Ken Waters Pet Loads though dated, is a good choice for your 4th manual. The Lee manual is another departure, which list loads both by weight and volume.