I own an i7-4770K for my main gaming rig and love it, but went with an FX-8320 on my office computer. I went AMD mainly because of the cost savings on CPU and motherboard. While I didn't need a powerful CPU, I did want a feature rich board with six SATA3 ports, USB 3.0 and 7.1 audio. The cheapest Z87 board was $100-$120 at the time and while I could have gone with a LGA 1155 system, the price savings were pretty minimal and I would be spending almost the same amount of money on a dead-end CPU socket.
In contrast I was able to pickup a FX-8320 and Gigabyte GA-970A-D3P motherboard for $155AR versus spending $320-$450 going i5/i7. I could have saved money and gone with a G3220 or i3, but again I would be spending about the same or more than I did with the FX-8320.
Now, energy consumption was a factor in my decision, but I figure that since the system isn't going to be at load 24/7 and only run 1/2 the day at most, then the added cost in electricity would probably be about $10-$15 more a year (maybe even less). in five years I figure I would have spent $50-$75 more on electricity, but I would have gotten to enjoy a better CPU and still spend less than I would have on an i5 or i7. Plus the initial money saved allowed me to afford other things like a SSD, which will pay off better dividends in performance than having gone with a more expensive Intel CPU.
In any case I was impressed enough with my FX-8320, that I bought a second one when I scored a $15AR ECS 970 motherboard. I plan to use this one for a gaming machine dedicated to playing on my big screen. Since I will only run it sparingly whenever I have time or am in the mood to play video games on the home theater, it make no sense to spend a lot on it. I could have gone Intel with a cheapo G3220 or i3, but I'm gambling that with this next generation of console games, that the PC ports will be better optimized for 8-core CPUs. I might be wrong, but it's only a $155 gamble.