I vote Cartier!
I have the Tank Louis watch for half a year, I got it from an authorized dealer that was a block away from the 5th ave store. They gave me a price that was before the price hike which just heppend at Cartier the the time. So I would really recommend buying from a AD, But then again I do live in NYC =P
Also, act fast Cartier does have price increase each year, like many other lux brands!
BTW I love my watch =)
GL!