I don't think there is a "best" manual, and a handloader should have a number of manuals to refer to. How many should be up to the individual of course, but I would recommend 3, the Lyman, one from your choice of bullet manufacturer, and one from a powder manufacturer.
Each manual has its particular niche. What I like about the Nosler manual is that it provides load densities for each cartridge, I wish the others would do likewise. The Sierra manual has a wealth of information on building all ammunition for hunting and target shooting, as well as a gas gun section that many others have ignored. I have Richard Lee's book, but I seldom refer to it, if he brings out a newer edition, I'll probably buy it and seldom refer to it as well. For the hunter, there is great information in the A Square manual and it has become one of my favorite reads, but the information is weighted towards his bullets naturally, and I seldom use his load data except when referencing loads for big bores. I've found more mistakes in the recent Hornady manuals than in any others, and the latest Barnes Manual has a disappointingly small powder selection for some cartridges, so it's better to use the older edition together with the new edition. If you just want a classy book for the coffee table, the Swift manual is very nice, but the data doesn't stand out much.
I have lots of other manuals as well, some are better than others, Ken Water's Pet Loads is another valuable reference, although it is missing some of the newer powders and bullets. He actually shoots the loads he tries and records the accuracy of the best ones. This brings up an important point. Keep good records when you are loading and shooting. If you are a hunter record the effect the bullet has on the game. These records will become the best loading manual you can get because it is representative of what happens with your particular rifle.