While some languages can be harder for a given native speaker, at the same time there will be speakers of other languages who will have an easier time. An Englishman may struggle with tones in the Vietnamese language, while a native speaker of Cantonese may feel right at home. Some languages do take significantly more time with the language than others to get to the same level.
The Foreign Service Institute (FSI) has created a list to show the approximate time you need to learn a specific language as an English speaker. After this particular study time you will reach “Speaking 3: General Professional Proficiency in Speaking (S3)” and “Reading 3: General Professional Proficiency in Reading (R3)”.
Please keep in mind that this ranking only shows the view of the Foreign Service Institute (FSI) and some language students or experts may disagree with the ranking.
If there is a language in this list you would like to learn and it is in a high difficult category, don’t let this stop you from learning it. Even if they are ranked as difficult, it does not mean that they are impossible to learn and maybe it is not hard for you at all.
Category I: 23-24 weeks (575-600 hours): 23-24 weeks (575-600 hours)
Languages closely related to English:
Afrikaans, Danish, Dutch, French, Italian, Norwegian, Portuguese, Romanian, Spanish, Swedish.
Category II: 30 weeks (750 hours)
Languages similar to English:
Category III: 36 weeks (900 hours)
Languages with linguistic and/or cultural differences from English:
Indonesian, Malaysian, Swahili
Category IV: 44 weeks (1100 hours)
Languages with significant linguistic and/or cultural differences from English:
Albanian, Amharic, Armenian, Azerbaijani, Bengali, Bosnian, Bulgarian, Burmese, Croatian, Czech, Estonian, Finnish, Georgian, Greek, Hebrew, Hindi, Icelandic, Khmer, Lao, Latvian, Lithuanian, Macedonian, Mongolian, Nepali, Pashto, Persian, Polish, Russian, Serbian Sinhala, Slovak, Slovenian, Taqaloq, Thai, Turkish, Ukrainian, Urdu, Uzbek, Vietnamese, Xhosa, Zulu.
Category V: 88 weeks (2200 hours)
Languages which are exceptionally difficult for native English speakers:
Arabic, Cantonese (Chinese), Madarin (Chinese), Japanese, Korean.
More time with the language doesn’t necessarily mean it is more difficult, though.
It is important to remember that nothing is impossible to master, it just might take you longer if the language is more different to the ones you already speak. Relative difficulty is arguably less important than personal interest and motivation. The hardest language is likely going to be the one you are least motivated to study, whereas even languages that are considered hard for speakers of your language are much less of a problem if you really want to learn them.
There is no easy answer to whether you should go for the difficult language or stick to the easy one. Consider how the “difficult” language you are considering lines up with your goals. Your goals will be the principal determinant of what you should do and how you will perform. The apparent difficulty of a language is best considered as an additional factor you should consider regarding time constraints or if you have a desire to learn quicker.