I'm not sure I could make the difference between batches. I've had A'bunadh regularly for a good while and I always love its ginger, cherry flavours.
It's a very tough choice. I love Glenlivet in general but I admit Nadurra is a bit surprising, the first time. Yet, I still love it. I agree with what was said: the Nadurra's body is not as full and the palate not as sweet; it's crispier and fresh.
If I had to make a choice, it would probably be A'bunadh, because it's so special. Then again, maybe this was the intention of the OP, to put for a choice two very particular, surprising whiskies. I think what I like above anything about the A'bunadh, it's those flavours you don't find in any other whisky; it's just one of its kind.