Wahahaha. I think we're opposites, then. I like editing the most, and my weakness is... writing that first draft. Guh. But that's just the literal "writing" part.
My favourite part of writing(as a whole) is doing all the puzzle work to figure out how the plot should go, and seeing the pieces finally click together in a satisfying way. When a story that consists of multiple pieces becomes a coherent whole, you get this immensely rewarding feeling. It's quite awesome to see your plot become the thread it should be - instead of a haphazard collection of events.
And my least favourite part of writing as a whole is... being unable to write as often as I want..