Ah, I was thinking you were saying "don't use F#, just use C#/VB.NET". Which has a valid use case, to be sure, but was sort of against the spirit of the OP's question.

If I was starting greenfield, with no SLA's about a particular runtime, I think F# would still be pretty high on my list, assuming Mono support was there. It's basically OCaml + huge libraries and a kicking VM. I think my next go-to for a bigger team, heavy typed language would be probably clojure.typed, followed by Haskell or OCaml, due to a combination of simplicity, power of language and typing, and my current comfort with each.