Yeah, I'd vote for Better Homes rather than the Joy. I've got both, but BH has a new edition out, with step-by-step diagrams of a lot of procedures. (I also remember that it was the mainstay of my ex-boyfriend, who was a reasonably competent cook.) It's more accessible, I think.
I use the Joy, myself, not so much when I want to branch out, but when I want a foundation reference for a basic procedure - f'rinstance, when I'm comparing two different "fancied-up" recipes and want to know what the essential bits are.
And I wouldn't dis Mastering the Art of French Cooking. Julia Child would probably be not a bad choice. She also is very accessible, amusing to read, and breaks down the seemingly complicated into procedures most people can accomplish. Many people count in their repertoires a number of staple recipes out of Julia Child.