My personal opinion - the best languages for learning are script-able, dynamically typed languages like Ruby or Python. You can build very basic programs in a procedural or functional style, and then get introduced very softly into the world of OO.

Haskell is great in some ways, terrible in others. Like the fact that you can't apply a normal function to a monad, and monads are hidden with do <- syntax, so you need to use monadic functions, and then there's type classes and shit... In Haskell it seems the complexity goes up exponentially and building anything beyond trivial is a huge hassle - no wonder 'design' patterns like FRP seem to be all the rage (while the entire computing landscape is being built on languages like C++ and Java).

Lisp/Scheme are conceptually very simple and easy to learn, but the syntax is hard to follow, and some of the keywords make no sense to someone who's never done any programming.

I personally think Ruby -> Java/C++ would be a great progression, with maybe some SML/OCaml on the side somewhere along the way. I spent way too much time dabbling in various 'trendy' languages like Clojure, Haskell, various Lisps and other FPLs, Ruby and JS/Node, etc... Now I'm at the point where I just want to build things, so I'm using a very practical, OOP, statically-typed, compiled language that many people have already shipped many practical apps with.... Probably not going back to 'trendy' languages.