first, sorry to hear this. But don't let unconsiderate others who say "toddlers are annoying" to deter you from flying. Those who can say this have never been a parent themselves, I feel pity for them not being able to enjoy the parenthood.

second, i would stick to J. However you should try the new J as other proposed, than old J. There's reason we call the old J "coffins" cuz they indeed are, which is why your son was so distressed. New J are lot more open, private, yet provide the neccessary eye contact to comfort your child.

third, the "A/D" or "G/K" combination offers much better interaction than the "D/G" middle 2 seats in my view. you can easily stand up to walk across the asile however middle is seperated by partition. Perhaps if you are travlling as 3, A D/G offers best option.

And lastly don't worry about others. If you feel worried/bad your son sense it so cry more. Just be confident. Yes there are unconsiderate others who makes harsh comments but look most are possibly free-bie op-ups this time of the year. Don't let the lowly Y op-up traveller make you feel less of yourself after you have paid the premium J fares. If they complain about your son's crying, they are more than welcome to go back to their seat 54E.