I prefer 9 over 7 because there is more room for my feet. I move a fair bit in my sleep so need the wider width for the footwell. If you do not move much then 7 is in the forward cabin so less traffic coming past you as two lavatories at the front of the cabin with another at 9.
I personally choose 1 and was in 1D this week on LAX-SYD. Slept very well. 1D and 9D are similar for the footwell.