[supersillyus]

Why not learn both? Pick a small but non-trivial application, and write it in both languages.

I am pretty familiar with and a fan of both languages. I started with Haskell, and found it to be really exciting. Go is very different, but after I got over my initial incredulity at it for not being Haskell or at least an ML variant, I learned to like it quite a bit. I think changed my thinking about programming at least as much as Haskell, perhaps more.

I wanted to end this post by trying to answer your question, but I don't think I can. It's like asking, "Should I teach myself the piano or the guitar?". The real learning comes from what you make, not what you make it with.