Regardless of the responses you get here, you need to tell us what your main interest is. If you say "everything", the is no best all-around lens. I gave advice to a fellow who had asked the same question, and when I suggested a moderate wide to short telephoto, he complained that it couldn't shoot 1:1 macros. Well, ****. Be more specific.

My choices:

Sports: 70-200mm f/2.8L
Landscape: 24-70mm f/2.8L or the 17-40 f/4.0L
Wildlife: 300mm f/2.8L IS

For just a walkaround lens? the 24-70 f/2.8L.
Inexpensive? Definitely not. Good glass? Yes.