Both equally regarding undercarriage washing. IMO it's up to you how you like the final wash. Like I'd advise getting a single wash at both places then just taking a look at the results. Then compare that to other stuff like location convenience.

Like I appreciate all the great free vacuums at Clean&Green. Also as an aside, not everyone cares...but clean&green uses less than 15gal/car wash and uses earth friendly chemicals and solutions.