I believe the latest Hornady manual (10th edition) is the most recently published among the major bullet makers. So it should be fairly up-to-date with regard to latest powders, Hornady bullets, and cartridges. I have the 9th edition Hornady manual and consider it inadequate for a beginning re-loader due to a rather sparse reloading procedure section. Not a big deal for seasoned reloaders, and perhaps that' shortcoming has been addressed in the 10th edition manual.
Though it's dated, I value my Speer manual the most. I really appreciate some of the minor details that other manuals lack, like the additional reduced power data for some of the revolver cartridges, and the 22 Hornet data utilizing small pistol primers for better performance.
Though it is somewhat costly, there is value in owning several manuals, especially from the makers of the bullets and powder you're using.