Ok, out of the two, I'm going to choose Carlin all the way. You can't beat Carlin because his stand up was like aesops fables a lot of the time, where you learned something out of it and carried that philosophy off with you.
I also think a really good combination of the two is Louis CK, if you haven't watched louis CK's stuff. He's got the great story telling of Bill Cosby with the verbal abuse and creativity of Carlin, whilst also instilling the same philosophies which is nice.
I love Eddie Izzard, it will be impossible for him to be debunked in my mind as my favorite comedian. Though, I recognize that he is not the best comedian, He can get a little convoluted at times toward a general audience and lose them, but he is brilliant.
Robin Williams is another strong candidate depending on his stand up, he is so much faster than everyone else that he holds the crowd because if you don't follow him, you're fucked.
Not too big on Prior, just because I've not seen a lot of his stuff (Though his 2001 bit is perfect)
I hate Lewis Black because he always seems like he tries to hard to be angry.
I'm not too keen on Insult comics so I'm not overly big on Don.
Dane cook is good, not the best, it's hard recognizing his talent just because he's very mainstream and you think you'll be judged as not knowing what you're talking about, but he is good.
I think someone who does Dane Cooks stuff better than him is Pablo Fancisco, I think that guy does crazy long winded stories best.
These are most of the comedians I like and listen too, say a line or two, but out of the two I'd say Carlin, though I think CK, despite not having as much material is beginning to pass Carlin.