Saoshyant
Headphoneus Supremus
Personally, I've never heard of somebody enjoying the E12 over the C5. They're both very popular in basshead threads of this forum that I frequent. Some think the E12's bass boost might possibly hit harder, but the main contributors to the community use the C5 with its smoother and more open, detailed sound.
I'd certainly have to concur with this assessment. The C5 for me at least was the next step past the E12, giving my HD700 a better sense of detail and spaciousness. Plus the bass sounded amazing.