Well, I echo many of the comments already made.

1. Book EARLY. SA is a complete nightmare - always.
2. From experience, I can absolutely confirm, you raise expectations to F and there is NO going back (then you would be a cheapskate for ever more if you dared travel anything else in the future!!)
3. Personally, I would choose J. You will have your eyes closed, both ways, for most of the flight. Get on the upper deck and it will be just fine.