The definition of what makes a "better" watermaker varies by cruiser. Some makes are energy efficient, some produce large amounts of water in a short time, some are very quiet (I once had one that sounded like a jet engine about to take off).
All current models are reliable assuming they are treated correctly. Watermaker membranes are common across all models and they are very susceptible to chemical contamination so one needs to be careful not to run it in water with oil or other chemicals. Chlorine (found in many municipal water supplies) will ruin a membrane in short order; and watermakers backflush at the end of a cycle. Bacterial and other growth starts quickly in a membrane, so they like to be used frequently.
The prefilters will clog up quickly if run in the type of water often seen in anchorages. I've had to replace both filters on my watermaker within an hour while running it off Prickly Pear - the sediments whirled up by the current make that water pretty bad. At sea (even in the Sir Francis Drake Passage) or in water that one can see items on the bottom in 20 feet is clear enough to keep the filters running for a long time.
I have a Spectra - it is efficient, quiet, produces 150ppm water but only makes about 15 gallons per hour; enough for me but probably not big enough for a charter cat with 8+ people aboard.