Best in both categories is certainly subjective but my personal best list includes boats like the Arenui and the Maldives boats - see liveaboard.com for details. Four Seasons Explorer could be one of the best in the Maldives but both Aggressor and Explorer have boats there also.
Also Raja Ampat or Komodo are supposed to be pretty special. I've never been to any of these places. I'm kind of like drrich also, much over a 12 hr. plane ride or multiple connections and I start looking elsewhere. I don't have a full set of carry-on gear and if you time your arrival to the sailing day better hope your luggage makes it.
Best coldwater, the Galapagos or Cocos Islands. Best with reasonable travel from Phoenix (I live here too) probably the Mexico boats. Rocio Del Mar, Solmar V and the two Nautilus Explorer boats. Solmar V has a youtube channel so you can see all the Mantas, whale sharks, hammerheads, dolphins, big tuna, sea lions etc. they encounter on every trip.Those trips are mostly winter spring though then they move over to cage dive with the Great Whites off Guadalupe Island.
Rocio Del Mar moves up ocean to Rocky Point - you can actually take their shuttle from Sky Harbor to the boat - they picked my buddy up at his house in Glendale. It's good warm water diving, lots of sea lions etc. Popular though - all sold out this year and part of next.
Belize is a fairly easy connection from here since Southwest started direct flights from Houston or Denver last fall. I expect they will eventually fly direct from Phoenix also if they aren't already. Read drrich's trip report - he's done it - I haven't.
Another option could be the Kona Aggressor - there's a direct (maybe non-stop?) flight from here to Kona that due to the time difference leaves in the morning from here. Cab to the dock is your other expense since I believe they bundle everything else in the price. They mostly dive south Kona where most of the dayboats don't go. My buddy did a dive in the area once and was joined by a couple hundred spinner dolphins. It's called the cellphone liveaboard in case you need to stay in touch with someone here.
We did the Turks/Caicos Explorer also. Really
early flight thru CLT to get there about 1PM. The boat typically doesn't sail till high tide at night. It's good deep wall diving with a lot of big pelagics and dozens of reef sharks, stingrays etc. Most seemed un-caring that we were in the water - I followed some sharks around more than once while they poked around looking for food. At one mooring doing my safety stop on the line I counted 24 Stingrays within visual range.
As far as fees etc. most spell them out - either on their fees page or in a FAQ. Typical fees include port charges/tourist tax plus depending on location a fuel surcharge could be up to $200 more. Also Nitrox might still be extra on some boats.
I tip 20% since the crew works hard - besides manning the dive deck, guiding on request etc. most double as wait staff and housekeepers as well as pulling watches.
Explorer also is offering up to $600 off on some trips this summer. If this is for a future trip, get on their mail list as they have an annual sale also.
I
personally wouldn't do any of the Bahamas boats - my buddy did Aggressor a few years ago and said it was meh. Also they've had both a crown of thorns and now invasive algae at some of the sites they dive. There's many other options in the Caribbean that are better IMO. drrich is correct that the Explorer boat doesn't dive St. Maarten but you fly into there and out of St. Kitts - or vice-versa since they turn the boat.
I wouldn't do the Cayman Aggressor in the winter either - it seems like they can't make the crossing more often then and riding around Grand Cayman for a week 90% of the dive sites can be done from day boats - a few from shore.
Obviously hurricanes are a factor at most of the Caribbean locations also August? to November.
DivEncounters needs to update their website - MV Pearl ceased operations a few months ago.
M/V CARIBBEAN PEARL II IS OUT OF COMMISSION UNTIL FURTHER NOTICE.
I'm also reasonably certain that the Dive the World
Club program only applies to guests who've dove with Aggressor previously. I'd also point out that the booking window for their Red Sea trips ends tomorrow. From here we couldn't get there in in under about 36 hrs. with two connections when I looked at it once after they brought the boat online.
Last thing is as a single diver you'll share a cabin with someone at the listed rate. Single supplements typically run about 50-60% higher. If you're lucky and the boat isn't full often the crew offers the single divers the option of using the empty cabins - happened to my buddy on Rocio once.