Is your onward flight on a separate ticket? If so, BA policy is that you must collect your checked bags at HKG (regardless of any interline agreement with the second airline) and then check-in again for the onward flight, because the second flight is not on a oneworld airline - so no through-checking of bags.

Of course, three hours is enough time if your first flight is on time. But just look at the timings again for a 90-minute delay on your first flight.

Having no checked bags means that you can go straight through the transit/transfer stream to the onward flight without having to clear immigration and customs.