1. "favorite Lisp dialect": Scheme (Guile, Gambit, and MIT/GNU)
2. "favorite non-Lisp programming language": Haskell
3. "favorite standard library function/macro/feature": homoiconicity, i.e. both code syntax and data structures built from S-expression, which makes features like syntax-case feature possible, and the ability to implement declarative domain specific languages with Haskell-like type checking on large parts of your program at compile time. If every language would like this, my life would be soooo much easier and less stressful.

One thing I hate about other languages is complicated syntax that makes it difficult or impossible to do macro-programming. S-expressions are a minimalist syntax that allows lisp to be well-adapted to most any use case, and features like defmacro or syntax-case are very well designed mechanisms for doing exactly that. Other languages like Python and JavaScript have macro-programming implementations but they are so hacky and not very well designed compared to most Lisps, which have the feature built right into the language.