Used VOA the 2nd yr in a row. was 1st row Y from HKG and 2nd person to the counter. Most in 1st either had their Visas already or didn't need 1.
Seems those who had paid for expedite got their PP before I did all of maybe 3 mins. My UA flight was 30 min late and we were the only flight till I got my PP back and then saw a stream of folks entering the PP area.
Id say as long as there aren't a few flights coming in when yours is VOA is the way to go.