AMD, period.
Seriously though, ever since I heard from The Screen Savers (TechTV a couple years back or more. I miss them, *sniffle*) that AMDs were overall better, and having 2 AMD computers in my house, I can compare them to the pentiums at my high school and the AMDs at home are definitely better.
I also find that it doesn't matter what generation processor it is, AMD is just better.
Finally, I believe the reason why the salesperson may have been telling you that the AMDs were better is because Intel recently faced lawsuit from AMD because of some unlawful practice. I think it was unfair advertising, monopolizing, or something to the effect where AMD was just pushed out of view of potential buyers.
-Joe
PS: this is not to be mistaken as an advertisement for AMD.