Scheme has an edge for education in computer science (which has different goals than teaching you actual Lisp programming) over Common Lisp, because there are some good books and courses based on Scheme.
For learning Lisp programming, Common Lisp has also extremely good books. Both basic, mid-level and advanced.
Examples:
Touretzky, Common Lisp: A Gentle Introduction to Symbolic Computation
Barsky, Land of Lisp
Graham, ANSI Common Lisp
Graham, On Lisp
Winston/Horn, Lisp
Seibel, Practical Common Lisp
Weitz, Common Lisp Recipes
Norvig, Paradigms of Artificial Intelligence Programming, Case Studies in Common Lisp
I would recommend each of these books to people who want to learn Lisp programming or certain aspects of it.
GNU Guile is good. However, I think Racket has better documentation and learning resources. Both CL and Scheme are defined by standards so once you are familiar with one implementation you can pick up another with minimal learning curve.