What numbers do you require? If there was a metric measuring simplicity then Lisp (or perhaps a modern variant, Scheme) would probably win - it is a local optimum of language design, essentially just lambda calculus exposed via a very simple grammar (which aids meta-programming).
Such studies are very hard to do, it is almost impossible to factor out social preferences.
For me personally, I am most productive in languages like Haskell and OCaml.
I also seem to recall a paper from the 90s or early 2000s which compared speed of development & program execution between Lisp & other languages. Maybe it was somewhere on Ron Garrett's site? IIRC, Lisp programs were developed consistently more quickly than C/C++/Java/SmallTalk, and were normally faster than all but the very fastest C/C++ programs — but I could misremember. I remember that it had some interesting-looking charts.
What programming languages do you use? What numbers made you choose those ones? Maybe if you show me an example of some numbers I could help more.
I don't have the time to write up why I think Lisp is great, but you can find essays by many greater (and more famous) programmers than me such as Richard Stallman, Peter Norvig, Steve Yegge, Paul Graham et al. But really the only way is to learn it for yourself. There is a kind of enlightenment that comes with learning Lisp and I would recommend it to every programmer.
Got any hard numbers to back up that bold claim?