The main reason I want to see clean(er) or at least clean-ish cycling is fairness. I think the sport has the best potential for maximum entertainment when there's an equal playing field and the truly best talents, if they work hard enough, establish themselves at the top. The strongest and toughest guys, not the ones who are the best responders to whatever drug is en vogue or the ones who are willing to take the biggest risks with doping control.The caveat is that I would like to see clean(er) cycling, but don't care if the NFL cleans up. Maybe that's because I have a closer personal relationship with cycling?
I believe the cleanest cycling would be the most interesting cycling for the viewers.
NFL - eh, I can't blame those guys for doing steroids, their muscles are basically their crumple zones. If you're too slow or too weak, you're getting hurt. I also don't really blame doping (within reason) in MMA or boxing, and similar sports. But cycling is different.