If you're ONLY gaming, an AMD build is the better buy, especially if you plan to crossfire. The 790FX chipset is usually cheaper than any intel board that handles 16x/16x.
For anything else, intel usually wins. AMD's Athlon II and Phenom II chips were built to compete with Intel's Core 2 cpu's, which they do admirably. Nehalem-based cpu's (i3/i5/i7), however, nearly always win. Even the dual-core ones can rival most of AMD's quads.