Most definately the process. There is a certain point somewhere close to half way through as I see it coming together and its potential, and its almost like I start working better and faster almost becoming part of the medium. Thats the most enjoyable part for me.
I think it all depends... Sometimes just doodling can feel very rewarding-versus a simple request to make something for someone that you may not really be "into" or starting to just sketch and wowing yourself with a final product you didn't expect. Or something that you are releasing onto canvas or paper or computer can feel very rewarding during the process lol I dunno-makes sense to me