I like to think that ML languages, in general, are good to start to learn FP with.

SML by Dan Grossman is a great resource because it explains the concepts very well. Anything that you learn after will be easier, does not matter if you go for Haskell or F# later.

https://www.youtube.com/watch?v=a1fkhDjCHB8&list=PL-eVNDa9MN...