tl;dr. For job in London, Scala (unless you need to use .NET libs). To get good at FP, Haskell. In my limited viewpoint, I've seen much more Scala than F#, but

tl;dr. For job in London, Scala (unless you need to use .NET libs). To get good at FP, Haskell. In my limited viewpoint, I've seen much more Scala than F#, but that could just be my circles. Though I have also seen some cunning people advertising Scala positions as a crude heuristic to get better Java programmers to apply. For learning FP though, Haskell is the way to go. Specifically, with Learn You a Haskell For Great Good. I came at Scala after having learnt a reasonable amount of Haskell, but I think if I were learning FP with Scala it would be far too easy to mix up imperative and functional and find it harder to learn the functional style.