Or maybe Intel just makes better chips.
When I built my current machine a few years back, I compared not only things like raw speed, but safety features, compatibility, and other issues. As just one example, Intel chips had temperature cut-outs that shut the chip down safely in an overheat. AMD chips just melted. To be fair, that was some time ago, and I don't know what the current situation is.
I'm pondering a new system with Xeon dual and quad-core units right now...