Why S&W or Bushmaster??? Any particular reason??? I would look around at all the different manufacturers to see what's available and the different features each one offers. Once you have an idea of what you want, go to as many gunshows as it takes and get your hands on them...it'll help with getting an actual feel for it. Don't get me wrong, Bushmaster is a good choice, but so is Stag Arms, Rock River Arms, DPMS, so forth and so on.
United States Marine Corps '94-'00
“No person was ever honored for what he received. Honor has been the reward for what he gave.” -Calvin Coolidge
"The deadliest weapon in the world is a Marine and his rifle." -Gen. John "Black Jack" Pershing, U.S. Army