It depends. Right now, I believe that the languages that are more similar to your first language(s) will be easier to learn than languages different from them. For example, Greek and Spanish were not so hard for me, I am still learning, and I am most certainly not fluent, but because I am a native English speaker, that helped me a lot with learning the grammar and vocabulary of Greek and Spanish because there are many similarities between these languages, especially Spanish and English. But with Arabic, it was a different story.
I have a friend (well, she is like my sister) in the Middle East who’s first language is Arabic. She told me that Turkish, a language like Arabic, is not hard for her to learn. In general, that should be true across the board: Asians have an easier time learning Asian languages, Europeans have an easier time learning European languages, Arabs have an easier time learning Arab languages, etc. etc. etc.