Keep the collar. It's the biggest visual identifier (along with the symbol of course) they clearly defines this as the DCU Superman. Things can be tweaked, but the core pieces need to remain the same. Otherwise, IMO, it's not HIM anymore. Keep the slightly looser "make him look huggable" fit, too.
Only thing I'd changes is getting rid of that sort of flap thing on the back of the collar, shortening the cape (it ruins his silhouette, especially when flying) and make the yellow S on the cape a touch bigger. And make the lines on the shoulders and wherever else more subtle (if not do away with them completely.