Always facinated with the SPARC, NeXT, or SGI machines back in the day. Being a kid in the 90s.. always felt like reaching for something that would I would never see let along touch.
HP-UX was very nice too. I used to love its desktop, VUE (that was later boringified into CDE).
I was offered a Xerox Lisp Machine to take home by a former employer in the mid 90's - I wish I'd taken up that offer!
Not forgetting the DEC Alphas!
Indeed, these were the machines to have for a long time! My first UNIX account was on a SPARCserver 670MP (Grex, if anyone remembers that) and definitely colored my opinion of what a "real computer" was.