IMHO, the Yacthmaster is not the first choice amongst Rolex enthusiasts. You usually get it only after you've already got your Daytonas or Subs or GMTs.
Sub/YM : Sea
GMT : Air
Daytona : Land
Well, amongst the models, the diver genre is the one most accessible to the general public; that's probably the reason why most of us own a couple of Subs (whether ND, D, TT, etc) in our collection. And for different time zones, the GMT simply represents value for monies so we tend to get this next.
In my personal experience, the next piece between the Daytona and YM depends on how you like to add on to your collection. Personally, for the chrono genre, I am more of a Speedy fan in view of its space association and history. And only with the YM could you get more precious metal such as platinum within the Rolex's sports watches. Plus did you know that the YM genre was originally created as a more luxurious version of the Sub; but Rolex was concerned that it might dilute the toolish character of the Sub, so a new YM namesake was created. But it was designed and originally meant to be an extension of the Sub family. And pieces like the YM40 continued to look like the Sub of the past, with thinner case and slimmer lugs, a more gentleman version of the maxi-dial and maxi-lugs Sub if you will. So it really depends on how one wants to add up to one's collection.
Having said that, it doesn't really matter... as we tend to want one from each genre anyway. So sooner or later, you would have experienced all of them in your collection, whether together or one after another.