Well , seeing your previous languages , i think you would benefit from learning a functional language .
All three of your choices are somewhat functional ( LISP is a proper functional language but not pure ) , so any of them would be quite fine for learning purposes .
But here's what i think
LISP -> This was my first language and even though i love it i warn new people to stay away . Why ? Old and starting to show its age , syntax might seem weird to someone used to other languages , shrinking active community ( emphasis on the word active ) , not very useful ( unless you're using emacs :/ )
If your considering LISP .. i might suggest taking a look at Haskell
*Completely functional ( its even pure unlike LISP )
*Its newer but its not retarded . A really huge amount of work and time went into it .
*Make sense syntax
*Awesome and intelligent community ( many of them ex-LISPers if not most )
Perl -> I really like perl . Its an awesome scripting language and really great for glue code but some things should be said : its a total hotchpotch , even after a year with perl you wont understand other peoples code , documentation is good but confusing when different sources use different syntax ( pragmas ) and style .
If you're looking at Perl , consider scala
*Multi-paradigm like perl but i'd say done better
*Based on JVM , so it might be good for you seeing that you've never used Java or any other JVM based language
*Upcoming language which translates to exciting
*A lot of people are backing on it ( Twitter ported its backend to scala )
*Good concurrency and parallelism support ( the way to the future of multi core and cluster machines )
Ruby -> Probably my favorite of the three because of its clear and concise syntax and ease of use of Ruby gems ( libraries ) but the only problem is a lot of the Ruby community is just Rails people so pure Ruby documentation is way less than it seems .
So go for Perl if you're up for it , Ruby if you want power but with ease of use OR if youre open to it , dip your toes into Haskell or Scala ( i'd say Haskell , because personally i just love it )