Great idea on the poll. I'm interested to see the results come in.
I second the notion of temperature control and pitching rates as essential.
But I think a lot of it is good technique throughout a batch. Did you calculate everything... correct mash temp and sparge temp, good rolling boils, correct timing and measurements of hops, storage of any and all things, proper cleaning and sterilization, adequate time in the fermenter/maturation, proper amounts of priming sugar, proper bottle conditioning temperatures, etc, etc. Mess up on one step and it could affect the result.
IMHO you need to watch someone do any entire batch to really appreciate what they do different from other brewers. But then again, that would be pretty boring to watch...
And the poll seems like it will be much more satisfying.