The Mclaren is probably the best looking car in F1 tbh. I didn't like the Mp4/21 at first, but it's grown on me all year. The Super Aguri (Arrows) looked nice to begin with, but it's be sprouting a load of ugly bits n bobs all over it, very messy indeed. I had a close up view of the body work at Silverstone and it looked very hap hazzard indeed. The Mclaren is very clean. Well it was until the snapper they had taking their official pr photos of Hamilton accidently whacked it with his lens!
The Williams is an attractive car as well, save for a few of the winglets, and the livery ultimately lets it down a bit. The STR is probably the coolest car on the grid.