Of these languages what are the best ones to learn?

In order of your listing (without indication my prioritization:

Spanish

French

German

Russian

Arabic.

Personally, I would put Russian, Arabic, and Spanish at the top of the list.

If you are looking for employability as a linguist, go with the ones that fewest people learn.

My choices were: Arabic, American Sign Language, and Signed Exact English.

When it comes to "best schools" the mere power of numbers would force me to say Spanish because more countries speak Spanish as a native language than any other. Then again... it depends on what you intend to study abroad.

If I had to pick five out of those i would pick:

1. Spanish (already have learned it)

2. Portuguese (already have learned it)

3. Mandarin (starting to learn it)

4. Hindi (super pretty sounding, India is a cool country, and it has a lot of speakers)

5. Japanese (really cool culture)

I would choose Albanian. The special thing about the language is that it really isn't similar to any other language. Sure it has some borrowed words from Latin or Greek, but it doesn't belong to any language-family tree.

Mandarin Chinese- best for business, Norwegian- best schools, German- also best schools, Spanish- if you want to go to South America or Spain, Arabic- for any country that has Muslims

It depends on where you want to go in the world as to which is best. The best in that case won't necessarily be easiest.

English will get you by everywhere. But if you insist, French, Spanish, Mandarin are the most important.

Spanish and Mandarin are most useful I guess.

Russian, German, French, mandarin.