I have manuals dating back about a half-century and published by Speer, Sierra, Hornady, Lyman as well as powder manufacturers' loading guides.

With few exceptions the manuals put out by bullet manufacturers concentrate all of their efforts on their own product lines. Fine, as long as you wish to load that specific bullet, but useful only as a general guideline when using others.

I have always found the Lyman handbooks to be excellent resources, including extensive lab-tested results for cast bullets as well as jacketed bullets by multiple makers. Also, the step-by-step guides from basics through advanced techniques and trouble shooting various problems are very good. If I were limited to only one I would choose the Lyman handbooks over anything else.