Prior to the Core series, I used Athlons (I had no interest in building PCs prior to that). Following the introduction of the Core series, I was unimpressed by AMD's response. Intel seemed to be the only option for mid- to high-end performance.
Recently, however, Phenom IIs and Athlon IIs have surprised me with their performance and value. Bravo to AMD for affordable, gamer-friendly CPUs.