Suggestions for an in-depth comparison of metaprogramming languages?

During the past semester I've followed a course on metaprogramming and reflection in which we have made an in-depth analysis of the languages Smalltalk (using Pharo) and Common Lisp. We've now been tasked with making an in-depth comparison of two other object-oriented languages in regards to their metaprogramming and reflection facilities.

As such, I'm on the look for two of such languages which are similar enough to be compared, but different enough have an interesting discussion. As a bonus, it would be cool to compare one mainstream language and one more research oriented language. I'm still relatively new to metaprogramming so it would be a big plus if the suggested languages have some good existing documentation and if they are not too hard to pick up. Other than Smalltalk and Common Lisp (which I'm not allowed to use, but are great candidates for other people reading this!) I have experience with Scala, Java, Scheme, C, Python and Haskell. Maybe one of these languages is already a good fit for my question, or a similar one.

Do you guys have any good suggestions and why?