What would be the most useful sign language to learn?

One doesn't speak ASL with English grammar -- as odd as learning French words with Japanese grammar. Like every signed language and spoken language, ASL is its own language. See ASL Tutorial for learning grammar to start with. read more

French is still a huge language and has always been (it used to be the lingua franca). While it might not be close to the others listed here (1.12%), it’s still useful to learn for many reasons and still has over 190 million speakers. It’s also the most popular second language for people to learn. read more

Reasons to learn Chinese Chinese Mandarin is easily the world's most commonly-spoken mother tongue: it has more first language speakers than Spanish (ranked second), English (third) and Arabic (fourth) combined. There are many other dialects of Chinese, including Cantonese, which is an official language of the special administrative region of Hong Kong. read more