While being on the East Coast is more central, I like either the North or the South better, with a slight personal preference for the North. The East Coast feels a little more exposed to the open water (rougher water), but you’d be very close to the best malasadas i found (about a block south of the LDS chapel in kapaa), the best shave ice (Wailua Shave ice) and some good local food options (Wailua Drive In). Also a shorter drive from the airport.
Kapaa is a fun town.