My main reloading manual is the Hornady 7th edition, it really is a good one (it also has linked material on-line. i.e. ballistics. etc.). If I were to choose ONE, it would probably be either the hornady 7th or the Sierra manual. I also use the speer 13th tho.
The best advice I can give tho is this. If you can afford it, buy at least two! There are some differences in powder charges/types etc. between two manuals most of the time, so you can cross reference and find out what works in your rifle.
Don't forget this one tho, it's free, and it's really helped me out a time or two.
Good luck and have fun.
Sample Hornady reloading section.
Red mist. It's an addiction!