Get the Tank. It is the iconic Cartier style, it will be recognized by everyone. You will have it for years and it will always look stylish on you. Get a neutral face, not pink.
I dont want my watch to be really feminine, but not too masculine either. So if was to get the Roadster, i would get it with the pink face, its kinda balance the whole thing out for me.....
The tank is bit conservative and feminine; more suited for someone who wears suits to work or dresses and heals. Judging by your photos, you seem to be the 'trendy, hip, fun' type of girl so I think a roadster is more YOU. And yes, go with the pink face as it adds a bit of feminine charm. Also, I like the band on the roadster more than this tank.