Well you go to watchcharts.com, and find the watches with a market price that's higher than retail. Namely AP, Patek, Rolex. Those are the popular gens thus they're the popular reps. Stuff like Tag, Breitling, Hublot. Panerai etc have market values significantly lower than retail. Instead of having to wait years on a waitlist you can typically walk into a store and buy one immediately at a discount.
The other variable is reppability. The Daytona movement is much easier to clone than the movement in the Moonwatch, and combined with the higher popularity of the Daytona is why we have essentially 1:1 Daytona reps but nothing close to a 1:1 Moonwatch rep.