From my understanding, American and Delta will only credit inter island flights from Hawaiian. And Jet Blue will only credit certain fare classes (I have a ticket with first class return, but premium economy departure and HA says only the first class leg will credit). The link is fairly unclear and I've had a thread with customer service going on that has illuminated only the above.

For a Delta predominant flyer, what is the best option to credit to?
For an Alaska Airlines/Virgin America/United flyer what is the best option to credit to?

Is the best approach a JetBlue account and if not a JetBlue flyer then use Points.com to transfer to something you do use? Of course, at less of a value than if it could be used directly.

I hate to have those decent level of miles stay idle in an HA account where I'll likely only fly to Hawaii once every 2-3 years at best.