Pet Loads and Lyman historically have been what I liked best. But lately I have been using Hodgdon powders a lot, so I look at their loads. I'd recommend a minimum of three manuals if you're getting serious.
Be aware that even the best manuals seem to have errors. I like to double check with other sources and then work with the loads starting a few percent below maximum and working up.
A recent manual showed 35 Remington loads heavier than 358 Winchester loads... Hmmmm...
