如果是住在美国的话， 一般情况下西班牙语对你来说会比较有利。 你有没有什么特殊的情况所以用 "需要学？" 我个人觉得你喜欢哪个就学哪个。 我对这 3 种语言都很感兴趣。 如果要排的话， 我是这么排的： 韩语 --> 日语 --> 西班牙语

不过我学的顺序是西班牙语 -->  韩语 --> 日语 (^^)" 

If you are living in the US, the most beneficial language is definitely Spanish unless you are living in a special area. Is there a particually reason that you use the word "需要学 (need to learn)?" If there is no particular reason, then I would say go for whichever one you love! :) 

I am interested in all 3 languages. If I need to order them, then it goes like Korean --> Japanese --> Spanish. However my learning order is actually different. My learning order is Spanish --> Korean --> Japanese. 

Maybe Spanish is your best choice because you can get the method of learning another language and it may help you a lot in learning the other languages, after all your mother language is English and you will be easier to learning spanish for you~

我觉得学日语吧。一方面我自己是学日语，日语的有些方面还是跟汉语有点相像；另一方面我听别人常说学会了日语再学韩语会掌握得很快。至于西班牙语，我自己没有接触过，不知道怎么样。

个人意见，仅供参考。不过日语确实有点难度。

我也是都喜欢。如果一定要选择的话，我选日语，因为很好听，呵呵。