Having been in J on an A350 a few times now, my observation is that there aren't really any bad seats. And there aren't any seats that are appreciably better than others, either.

The "is this a good seat?" discussion for premium cabins these days seems to me to be a hangover from the days of trying to get 1A/K in a 747, questioning whether 2A/K were marginally better, and avoiding 4E/F and 5E/F unless you were flying as a couple and didn't care for the view. Oh, and chasing the UD J seats in a 747, which really did feel like a halfway house between J and F with a good crew.

There are no "star" seats or areas as far as I have been able to work out on an A350, or an A380, or a 777 (where the main objective seems to be to get an aircraft with CS and not the old ying/yang seats). Yet to sample a 787, but doubtful that it breaks that pattern,