Depende in what language you know first for English speaker ps the hardest languages to learn are Japanese, Korean, and Arabic.
But it doesn't just depend on what you speak first it depends on you yourself. Some people can't say specific letter correctly or they have a really bad accent which leads them to be unmotivated and later give up on learning that language.
For me learning Arabic was easy, but I was very motivated and worked on it everyday so p, at the end of the day it just depends on you, on you and how badly you want it.
Hope this answered you question! ☺️
