Richard Mille

I believe for the time being the toneau case for RM will reign supreme, but that is just my gut feeling. In my opinion RM is associated more with a 'racing' theme, and as such their decision to broaden their horizons to dive watches is interesting. 

To answer your questions more specifically, I don't believe the diver is as popular as the toneau case. Additionally, if you are looking to buy an RM I would advise you to forget about resale value, as they are not high at all. You can go to the collectors market to see an indication. Ive seen iconic pieces such as RM04 go for some quite amazing prices. I just wish i had the funds to pick one up myself

If you can, go for an RM because you love the watch and all it represents. Because if you are looking for resale value you might be disappointed.

Best,

Rahul