I have never owned a Rolex, and don't see myself owning one - but only for one simple reason - they don't have a style that I like. I think that Breitling and Rolex are comparable, although the resale market clearly values Rolex higher.
I would like to see in house movements in Breitlings, but understand that requires a significant R&D investment that is ultimately passed along to consumers. However the lack of an in house movement is a mark against Breitlings.
I have been fortunate enough to be able to expand my collection quite rapidly and am now moving beyond just Breitlings, but Rolexes just don't do it for me.
If I was only buying as an investment Rolex is obviously better than Breitling, but there are any number of brands better than Rolex - and if I were looking for investment jewellery I would buy diamonds anyway.
I think there is nothing wrong with Rolex as a watch. It has more patents and prices than any other watch. Their presence in the world is incredible so you can take off your rollie and turn it into good cash if you find yourself in trouble in Tanganyika or you name it. But, it can be uninteresting to wear for some - at least for me -
About investing in diamonds - I'm sure you mean uncut - I would be really careful. Diamonds are easy to buy but difficult to sell unless one is already an established diamond merchant, and synthetic ones are difficult to detect even for the trained eye.