I would go for the seat in the 40's - it's a good location with access to different sets of loos and the galley without being too near to either = more peaceful but also handy if you need them.
Thanks flyers....I suppose just being behind the wing the view is a bit restricted...but being a nightflight from JNB to LHR..there is not much to see anyway over the dark contitent
I personally dont like middle rows 43-46 on the A346's as it's get's quite crowed as you are close to the washrooms and feels a bit closed in as you have the crew rest entrance bulkhead area in front of you and what used to be the mid galley, now the water fountain bulk head area behind you.