I've never ridden a speedy, so I can't say which is best. All I can say is that the difference between the demonstator bike with normal exhausts on and mine with the long TOR's is competely different - not just in sound either. The bike feels loser, and less choked.
I think the look is right too, you obviously get the slash's as standard on the speedy, which is good, but there was no way I was having the America without them.
I think the best advice really is, try both and decide - there is no right answer to your question.
Personally I prefer the America, but we're all different and thats what makes the world go around/to war etc...;)
Cheers,
JC