Yeah I like the button one too. It actually looks a little more like a uniform and with a little military thing going on. Superman's costume is classic, but I think Marvel's costume ranks up there with Batman's, Spiderman's, Silver Age Flash, Captain America's and Silver Age GL. Really, really classic - and part of a group (take out Spidey and GL) - that can also be seen as unique in silloette.
Good point! GL and Spider-Man both look basically the same in silhouette, but Captain Marvel is instantly recognisable, mainly thanks to the cape. It occurs to me that the Golden Age Flash is perhaps the most recognisable character in silhouette, because he looks just like Hermes. (I love his look, by the way; I hate it when people say "It looks like he's got a hubcap on his head".)