I enjoy almost all of it ('almost' because I am *not* a fan of sandwiching), and my favourite stage tends to vary a bit with my mood - sometimes you are just in the mood for cutting, or in the mood for fiddly piecing (strangely, I've yet to be in the mood for a bit of seam-ripping, but you never know LOL).
My absolute favourite bits are probably the daydreaming/planning at the beginning, the piecing once it is started and I can start to see a quilt emerging - tho I tend to lose steam in the middle (when it is in most danger of becoming a UFO) and then (assuming I persevere) get 'second wind' at it when I get close enough that I can see what the final top will be like. I love the hand-quilting (I don't FMQ, tho I have had a few LA'd, which is more of an instant buzz), and actually really enjoy binding.
So, most of it? LOL