I would agree with the others... with a caveat. There are manuals that are better for some things, and not so good with others. I needed data for Service Rifle... that's a Hornady book. I prefer the data format of Speer, and it includes a lot of the bullets I load. Obscure powders or crazy bullet weights? Lee. Jack of all trades... Lyman. I reference those, and sprinkle in online or downloaded data from Hodgdon, Alliant, Accurate (Western,) Nosler, and others. I even use... *gasp!*... data downloaded from the forums, but that data is compared pretty vigorously against published data for accuracy and viability. I had to do that for cast .348WCF data, for example, where there is/was very little published data.
Go out to the garage and open your tool box. Is there only one screwdriver? No, there are likely a bunch; even if they all do the same thing, they do it in different ways.