The most important thing about either lounge is the location of your departing flight. The Pier was built for passengers whose flights are at the end of the airport normally gates 60-80. As you know how the airport is constructed, once at those gates, it is quite difficult to get back to gates 1-17 as the train goes in one direction. You'd have to go to arrivals, then go through security again to get back to departures level - something that you need at least 30 minutes to do! IF there is no queue at the security check point!

Check which end your departing gate is. Regional flights from HK normally depart from gates 60-69.

My preference - the Pier. It's quieter, but does not have the Cabanas. But it's also less crowded. Day rooms are not recommended for claustrophobics!