Just my opinion, but the Solstice is hands down better than all the rest of them going to Hawaii to/from the mainland, especially the 12-nighter.
However, with that said, the POA is great for visiting the islands because it goes more places and spends more time at each one. The ship itself is okay, food is not all that great, staff is very good. But this way we got to spend several days on Oahu before the cruise, then we did the cruise, then we flew to Maui and spent a week there. A bit more costly, but we didn't have to spend 5 days at sea. Although, if I were going to spend that many days at sea, I would definitely want to do them on the Solstice.