Which language do Hong Kong people speak better? English or Mandarin??

I know Cantonese(粵語) is the most widely spoken language in Hong Kong.
Many Hong Kong people speak Cantonese as their first language.

Then what is Hong Kong people's second language?
Is it English or Mandarin(Putonghua普通話)?
Which language do Hong Kong people generally speak better?

Do you think the chinese mandarin replace the English like a global language?

what do you think i heard some people said that but if we study about the english in many conutries is the second language around the wordl and the chineses is a language tone so you can say 1 word like 4 differents forms and each tone mean different thing.and you can image the chinese in computer like visual basic.c++,etc...and the teacher say in china all the business are in eglish and you don't need to speak chinese sooo what do you think

Does anyone know any good websites with statistics about the Chinese language?

I'm looking for evidence on why people should NOT learn Chinese as a second language. It's for a debate.

Things like number of people who do not learn a second language, difficulty in learning Chinese and similar stuff would be most useful. I keep getting evidence for the other side... >.<
我会中文，但是我对英文的网站比较有兴趣。