I'm bias, so I'd say go the white dial (I have a white dial Datejust). The Explorer II is a very rugged watch, that will go the distance with wear and tear. Although rather common, a submariner of some descriptor wouldn't be a bad choice either for a first Rolex. Should you decide that it's not the type of watch for you, you can easily find a future buyer.

Another brand that sprung up in the back of my mind was Bremont (as worn by Bear Grylls, along with world record skiers and climbers) which are also rugged from what I've read. Slowly developing a love for the ALT1-Z *getting off topic*...