I love BIG SHIPS!!! Too many to pics to choose from. However the more detail within the colossal structure the better. Bonus points for clever use of lighting and shadow which helps portray size and majesty.
Seriously, of all the concept art I've seen turned into games, the Homeworld ships are some of the most awesome ships in the Universe to me! And I haven't even finished the first one! Damn you Mission 14!!!