I've use both Intel and AMD right from the days of Pentium 75mhz processors and i'd have to go with AMD as a final choice. they're far better value for money in comparison to intel and from what i've used they are much more efficient with the power that they have. As for Intel being better at multi tasking, i can't say i've noticed any difference really.
AMD have something to proove, and to an extent it is this fact that makes thir processors so good - they work hard to proove the fact that they are just as good, if not better than Intel; Just look at Intels marketing, it's far stronger than AMD, all the major system manufacturers sing the praises of Intel, Yet AMD still lurk in the background with all the new technology.
I'll stick to my AMD's thanks