This isn't really a fair question to be asking. These two are completely different players. Personally I think Richards will have the better career based on the fact that he won't be asked to be an impact player like Carter. Richards will be relied upon to do what he does best, play a sound 2 way game. Of course the Flyers will be counting on Richards, I don't mean they won't, I just think Carter has more to live up to at this point. That being said, I think Carter will have a great career as well.
I'm trying to understand how people are wondering how Carter fell to 11th spot. Before the draft Carter was tagged as a late 1st round pick, maybe 2nd round depending on where he fell. I'm sure the majority of people were quite surprised when he went that early. The only reason people are now saying that is because of the World Juniors. I don't think we should be talking about him being picked at 11 as slipping based solely on the WJC, especially when most would never have put him there.
Finally, there is no way Carter is a regular with the Flyers next year, provided there is a season. Carter is not ready for the NHL in my books. He has alot of filling out to do no his frame and he needs to develop a sound defensive game to fit in with Hitch's system. He'll need some time in the AHL to groom his game. Considering the depth of the Flyers up front, I really don't see the point in putting him on the 4th line to waste away when he could be logging big minutes in the AHL.