All those A320, A321 and 737-800 business class seats are almost the same. No bucket seats, but with wider central console area. Sure much better than the economic seats. Here is Copa 737-800



ZH A320



TK A321 Neo



And OZ A321 Neo.



The AV A320 is between those. Not any better. I recall the seats are older style. More like 737-8.

I never take any amenity kits, not even with SG. Just add more things to the landfill. It is mainly some toothbrush, eye cover and ear plugs to help to sleep.

Confirmed J tickets get you all the benefits, same as Star Alliance Gold level. Some airlines like Air China won't allow any upgraded J ticketholders to enter the lounge. I do not check in any luggage when I travel. So I care less about the bag benefits.

I certainly like the priority boarding, separate section and the attention from flight attendants.