F# is very much focused on gaining real-world usage by making it compatible with .NET. It has a lot of features that heavily target this, so for example the obj

F# is very much focused on gaining real-world usage by making it compatible with .NET. It has a lot of features that heavily target this, so for example the object system is built to be compatible with the .NET style of classes/objects (but sadly, they ditched the OCaml way of doing this, which IMO is much better). This introduces many inconsistencies in the type system and some clumsy syntax, which is pretty much a deal-breaker for me. However, these features are very specific to more advanced parts of the language. If FP+.NET or library support is a must for you, F# is probably the best choice by far. Also, F# does a great job at interfacing with the GUI parts of .NET, so if you need GUI (or Windows support) it is definitely the right choice. The core language is still quite elegant and a joy to use. I think if you have the choice not to use F#, though, that OCaml is generally nicer to use. It offers a ton of features that I find myself missing in F#, like a much more powerful module system, a more advanced approach to OOP, a cool macro system, and so many more (polymorphic variants, better exceptions/soon to be an effects system, ...). In general, I find the syntax to be slightly more predictable for OCaml, but a lot of people still prefer F#'s syntax (which is indentation-based, btw) so I wouldn't focus on that point. Overall, I think they fit different niches. I've had to use F# quite a few times and it's by no means a bad language, but after using OCaml extensively I feel disappointed by F# a little bit like how I'd feel disappointed if I had to write a project in Java.