I'd like to see the butt end too, but with that not in consideration, I would start on the left side. Meaning, looking at the photo, the left side of the log, the side that is vertical, I'd make my first cut there. The reasons are;
- Looks like the flattest/ straightest part of the log
- You will get some nice wood cutting thru the Y that way
- You could say the log has two Y's and the one you will be cutting thru first looks to be the better of the two.
- It really looks to me as though there willl be some significant bark inclusions just below the first Y you will cut thru (if you start with the left side). I'd want those inclusions kept in the pith cut if possible and I think there is a shot of doing that if you start the way I'm suggesting. If it's not possible to include the pith cut in with the bark inclusion area, at least the bark inclusion area will be in mostly one cut, not in all of your cuts if you start 90 degrees from the way I'm suggesting.