I thought hard about this one, but in the end I had to go with PL/I (the only one at the time of this post). I achieved a decent proficiency very quickly with PL/I and because of it I went through a succession of University jobs that ended up with the one I currently have.
in reply to Favorite programming language, other than Perl:
As mr_mischief mentioned I was also fond of Rexx--which I also used for glue purposes but once we switched from an IBM mainframe to Solaris boxen, both PL/I and Rexx fell by the wayside. It was a couple of years before I found out about Perl so we made due with fortran, shell scripts and SAS. HEY! What about SAS? True it started out as a statistical analysis application, but the ease with which you can sort and merge data sets is remarkable (plus the data manipulation tools aren't too bad).