I've used about 10 different Lisps - by which I mean, completely different Lisps, mostly in the pre-CL days, of course. I can't even remember most of them, although MacLisp was one for sure. I mostly remember the computers they ran on, which was many, ranging from IBM 360s to Apple ][s. I even wrote two of my own (which were used by literally no one, including me :-) and tried to make a micro-programmable PDP-something-or-other into a Lisp machine (which never really worked, although it did CAR and CDR really really fast!) Once CL came out ten thousand Lisp hackers like me breathed a major sigh of relief!