I believe it depends on where you live. Knowing the language that is commonly spoken around the community is a powerful thing for building positive relationships. In California, generally Spanish would be the language to learn although there are urban centers with large populations of other cultures. In San Francisco, I often wish I knew how to speak even a little Mandarin (although Cantonese is more prevalent here).

I am curious as to why English isn't at the top of the list.
I guess you are asking about secondary languages, but so many children are not English speaking when they come to this country, and many others, born here, are bary literate in the language of the US.

Students should learn at least two languages:

1. The dominant language of the country they live in.

2. The language of their home culture.

They need to know the country's dominant language so they can develop marketable skills and contribute to the economy. They need to know their home language because language carries culture with it. Each family has a culture that should be honored and preserved.

If, like my family, your home language is the country's dominant language, then you should learn a second language. It helps develop understanding and tolerance of other cultures.

Language is more than a means to express ideas; it is a way to transmit values, a way to develop higher thinking, and a way to embrace differences and similarities.

Ultimately, it really doesn't matter which language a student learns. What's important is that they become fluent in a second language. The process helps a student think globally, understand other cultures and value the efforts of those who speak English as a second language. Learning a second language builds confidence, helps kids organize their thoughts, and teaches students to stretch their envelope of confidence.

It depends on so many factors. For college bound students, probably French, but any romance language will help. For diplomacy, sports, French again. Most of the times for regular jobs in the U.S., Spanish. For psych majors, German.

Most importantly, learn a second one, then another, then another... English is my second language, but I also have French, Spanish, Greek, Latin, (I know, dead languages..). German, and I am now touching Japanese. My kids know at least three languages , two or three fluently. It allows them to travel and get a lot more real contact with local people.

I teach World Languages and English, and I don't understand the hangup about starting; it improves your mother tongue to learn another language, if anything.

I believe that everyone should learn the language of the country in which they live (or at least make an attempt to learn it. I am the granddaughter of immigrants and my grandparents never fully learned English). Those who know only the language of their country should learn a second language of their choice. If a person (unfortunately not me), has an “ear” for languages they should learn as many as possible. To me “learn” could be interpreted as everything from conversational to reading and writing. In my opinion, as the world shrinks knowing multiple languages will become imperative.

First and foremost,all students should know English,real English,not "textspeak"or ghetto slang. I have had students answer questions on an assignment with "idk" or some other made up language.How can one express themselves by using mediocre speaking/writing skills? Our kids aren't dumb, just lazy!

It doesn't matter too much which language a student learns first after his/her native one.
Learning the first foreign language is always the most difficult, because one has to learn both the language itself and how to learn a language. After that, subsequent languages can be picked up much more easily. My own experience was that after extensive formal instruction in French and minimal formal instruction in German, I picked up five other languages on my own, two of which I speak pretty well now, and from one of which I published a book translation into English.

I chose Spanish because except for English, that is the predominant first language spoken in the area I live. (California)

English!
The questions asks "what is the most practical language ..."
Considering what we often see, English needs to be much better learned!