The reason there are so many choices is to suit the plethora of shapes out there!
For more relaxed posture touring, there is the B17. For sit up and beg, the B66, B67 or Flyer. For more sporty riding, the Professional or Swift. for racing, the Swallow.
Really, it all boils down to the shape of the derriere and what feels comfortable.
I'm on the larger side, so the wider B17 and Professional fit better then the narrower Swift, though i have found the Swallow fine as well.
My current seat of choice on the everyday bike is the Spa Nidd - same as a B17.