As nitesite said there really isn't any one 'best' manual.
Sierra, Speer, Hornady, Barnes, and Nosler list data that they developed using their bullets. You can use this data to work up loads for different brand bullets with similar weights however.
The Lyman 49th manual is good because they don't stick to a particular brand of bullet. They also have load data for the bullet molds they make if you cast. The Lyman 4th Cast Bullet Handbook has data for Lyman and other cast bullets.
The Lee manual is basically a compilation of everyone else's load data. However, it was published in 2003 and hasn't been updated since, so new powders/cartridges aren't listed.
The Hornady manual, like the Sierra manual, has special section for the AR-15, M1 Garand, and M1A.
My go to books are the Lyman, Hornady, and Lee. I have the Speer 14 manual but basically never use it. I'll pull it out if I want to load up something hot because the data in it goes higher than all my other manual, sometimes by quite a bit.
Since you mention that you are new to reloading, check out "The ABCs of Reloading" by C. Rodney James. I've never read it myself, but it comes highly recommended for beginners on every forum I'm on where reloading is discussed. You can find it on Amazon. The latest edition is 9.