For me it varies from story to story. There have been stories like Broken and BMS that I loved writing so much, I can honestly say I enjoyed the process as much as or more than the final product. Then there are those stories, like Secrets of the Heart, that were a total pain in the ass to write, but once I finished them, I loved the final product.
I also look forward to the readers' reactions, which makes me want to rush through the process just to get to a product I can post. I'm trying to make myself slow down and just enjoy the process.