I dove with Panunee this past April and I enjoyed the trip very much. I had not try many other boats but from what I gathered from other people who have been on several other boats, basically Panunee, Divemaster 1 and Aqua One are probably some of the best boats available in Thailand.
I was very happy with all the staffs on board. The dive masters were all friendly, accept one but he was sick the entire trip so I would give him the benefit of the doubt.
Other people told me that Dive Master 1 has better food and the service is a touch better, but I have not personally experience that. The only complain is that not all suites on Panunee have private bathrooms. Otherwise the facility is very nice. Diving wise, I think most boat will be about the same since they all go to similar spots.
As far as is it worth it, all I can say is that I already signed up for their Phi Phi, Similan, Richeliue trip early next year.