I think ti's fallacious to consider things as matters of "programs" - CF isn't a program either, anyway. And CF is freely borrowing from other schools of thought that did the real hard work. It's not a matter of "improving CrossFit", but ignoring it and finding out where they were getting their ideas from. There's nothing there to improve because they say, "Oh, yeah, everything good from the S&C literature about functional stuff, yeah, sure, we got that, too, it can be a part of CF, sure." CF really added no value there.
Anyway, the first thing to ask is, what are the goals you're after? If you're after becoming a good 5K or marathon runner or even a rower or biker, there's a lot of literature about best practices. If you're after becoming a powerlifter, there's a lot of literature. If you're interested in strongman, not as much literature, but there are ideas from the practice of professionals and from the S&C community.