Ah, I did wonder at how I'd never noticed this before. I think Routh and Cain were both saddled with suits which failed to make the most of their physiques. If you watch the extras on the SR discs, Brandon was really well built but the suit sort of compresses his muscles. Also, IIRC, Singer said that he didn't want him to look cut or ripped (I'm paraphrasing but that was the gist of it), just strong so they didn't give him the sort of veiny look that Cavill has in MOS. Cavill to me looks to have been in the best physical shape of any actor to play Superman but I think he's helped also by a suit which does the most to define and show off the body of the actor playing the role. Obviously the colour and texture aren't to everyone's taste as this thread shows but it definitely does a lot to flatter the person in it. Not that he needed much flattering, obviously!