I've always considered the GMT Master to be my favorite Rolex. A Submariner is always a safe choice, but you do afterall see them everywhere. Not that the GMT is a rarity by any means, but it's just that little extra panache that does it for me. Give me a GMT hand, a faded bezel insert, some yellowish patina and I'm sold. As you already may know, the present day GMT Master has a ceramic bezel. While an interesting (and inventive) choice, you are always going to have to put up with purists that refuse to acknowledge any other material than steel in their watches, something especially true in some circles of vintage Rolex nerds.
It may then be worthwhile to note that there is a precedent in Rolex's use of certain exotic materials in the GMT Master. Early on in its life (being born in collaboration with Pan-Am Airways, the story has it), the GMT Master featured a bezel made of nothing other than bakelite. An an outdated acrylic type of material, you can still find bakelite in old radios and certain telephones. An interesting choice, even back when bakelite was at its height of popularity in the plastic industry, bakelite is rumored to have been chosen because it was easy to work with, and the only way to apply radium to the numbers on the dial.
The good news? The lume on these watches are pretty fantastic. Some even glow to this day. The bad news? Bakelite isn't exactly the ideal material to use in a sports watch designed to be banged around with. The bezel cracked relatively easily.
Even so, Bakelite GMT Masters have become quite a gem and highly sought after. Their very short production run (not more than four years) as well as their important place in Rolex history have made them a hit among serious collectors. Luckily, there's a late (1959) example in astonishing condition (and a fair price, too) for sale right here on JamesList. Don't miss out on owning a piece of watchmaking history.
Thanks to Rolexness for the picture.