From the standpoint of looking good on the sea, what ship do you think of as your favorite. I hate to say it but some of my favorite ships don't look all that appealing to me from a sea-going appearance perspective. Many of these new ships remind me of a big city's floating condo development, ready to tip over.
I've never been on it, let alone any Cunard ship, but I've seen it, so my vote is for the Queen Mary 2. I might add the Queen Victoria and the Queen Elizabeth also look darn good underway. Those two are refined versions of Carnival Corp's "Vista"-class ships, which share the same basic platforms, other examples Carnival Legend, Carnival Miracle, Carnival Pride, Carnival Spirit, Costa Atlantica, Costa Luminos, Costa Mediterranea, Eurodam, Niew Amesterdam, Ooserdam, Westerdam, Zuiderdam.
I guess I prefer ships with a lot of "rake" in the bow. What I dislike are the plum bows where the ships superstructure extends way forward. That makes a ship look like it ran into a cliff or something. Example: NCL's "Pride of America".