In general operations, the INTEL i7 will be faster. Maybe 10-20% faster (on certain benchmarks) but it is also twice the price. Make no mistake, the AMD line of CPUs offer a great value and that is why I like to use them.
In most single threaded benchmarks, even the i5s will be faster than the AMD 8-cores. However, when you start running heavily multi-threaded applications, the AMDs are pretty darn good. Running Linux and multiple VMs, they perform very, very well.
Below is a typical workload of running 6 medium size virtual machines (ranging from 2-4GB of usage). I consume on average 20-26GB of RAM out of my 32GB. I can assign separate cores per VM.
And in general, the VMs run quite well. AMDs make great Linux Dev builds. With a good AM3+ mobo, 32GB of RAM, you can build a nice box for well under $400.