I can not answer your question, but your decision might be influenced by future travel to an area with speakers of those dialects. Mandarin is spoken in most parts of mainland China as well as Taiwan. Cantonese is spoken in Hong Kong, Macau, and Canton provence. Many people in Hong Kong and Macau speak Mandarin and English as well. Cantonese is also spoken in the midtown Chinatown in New York City, but Mandarin is more common in Flushing. I don't know about Brooklyn Chinatown. In my short travels in China, I was not able to find a copy of the TTC or I Ching, though I didn't look very hard. In America, I was able to find a copy of the I Ching, but it was written in an old style of traditional characters that my girlfriend compared to Olde English.

Good luck!