I personally like F on the 789 better; however, one of its drawbacks is that the cabin tends to be fairly hot. The temperature can be 20C in the galley and 24-25 in the cabin. Crew told me that the space is fairly small, the airflow is disrupted by the thick curtains and therefore it gets to be a bit of a sauna. I found it's worse in the first row rather than in the second.