In addition to what Sandra said, you might want to consider if you're willing to travel abroad and the countries you'd like to visit. It's always nice to learn the native language so as to communicate with the locals and move around as easily and smoothly as possible. Good luck!

It depends what your goals are concerning the language. Considering you're a native Mandarin speaker, I'd suggest Japanese/Korean, as those languages are closest to your native language. You'll see results quicker. But if you're super interested in German, French or Spanish go for one of these. It's more important that you pick a language you're interested in, than to pick a language, because it's easiest for you, or because other people speak the language. Pick something you are truly interested in!

It reminds me when I had to choose a 3rd foreign language at high school, i had to choose between Spanish, Italian and German. But i wanted to learn all three. Knowing that German was harder, i thought if i would learn it later on my own it would be more difficult, so i picked it, because i knew it would be easier to learn both Spanish and Italian later without much difficulties. That's what i did few years later, I took Spanish course , then few years later took Italian in parallel with Russian. If i was to give you an advice, i would say pick French or German first, then you can go for Spanish which would be easier after learning French. I think Korean and Japanese would be easier for you to learn, you can learn them later or in parallel with other languages.

Well, you already speak English and seems to me Chinese. Pick a language which has the least in common with the ones you already know, that way in the future it'll be easier for you to learn other languages. Korean and Japanese are pretty similar to each other. Spanish and French have a lot in common too, also they have a lot in common with English. They say German has much in common with English but I personally can't confirm, haven't noticed that similarity. Basically, my advice is - pick the language which is as different from those you know as possible.

Hello! I'd say that you should pick the one that's the nearest to your native language. In this case, it'd be either Japanese or Korean. If you learn a different language with a similar grammar or similar word etc it will make your learning progress much faster and easier! German, French, and Spanish look good too. They have different rules and words but since you are a Chinese speaker i think you will have more struggles than learning Japanese/Korean. However, if you are very interested, go on! It'll be a challenging one of course :) Aand, consider the goal why you are learning the language. It will show you a clearer decision of choosing a language for you. Hope it helps and good luck!