If you want to be completely open source. There seem to be a lot more libraries and general capability with the specific license we need. I really should have clarified better, I seem to have lost a word or two in there.
What I'm working on needs to interface with many different existing modeling and optimization efforts at some point, and of the options out there Python seems to be the most understood by the largest group of people (statisticians/scientists/programmers). With python we can keep everything 100% open and available to the largest number of people.