男方是港人,女方是廣東人,請問在港註冊和在內地註冊對申請單程証和生BB來說那種比較有利?

No difference for one-way permit and child birth.

However, Hong Kong is a better location because:

1. The process of marriage registration in Hong Kong is simpler than the Mainland.

2. The process of obtaining civil document (marriage certificate, birht certificate, etc.) in Hong Kong is simpler than the Mainland. Also, civil document in Hong Kong is issued in both English and Chinese, so that they are easier to be recognized worldwide.