I prefer to use Ruby when possible, though I switch to Python (with numpy) for more math-heavy applications. Ruby's ability to chain methods, syntactic sugar, and larger amount of built-in methods makes programming much more fun and efficient than Python, where I'm constantly going back a word to write a new method and enclose what I just wrote in parentheses, or counting parentheses/brackets, which I don't really seem to need to do in Ruby. Python is still much more enjoyable to program in than most other languages, but compared to Ruby, it feels like programming backwards. I also prefer to use Ruby/Rails for prototyping and web development.