No difference. (I just have personal preference to the J side). But, if you are traveling together 2J/3J would be a bad choice, IMO. 1CD (center) are very nice, since they are slightly offset from the rest and very private if traveling with a companion. I would, personally, never travel with someone and NOT sit in the two center seats. Well, unless you have absolutely no desire to interact with that person for the flight. Also center seats have a nice amount of extra space (or at least it seems this way) in the center when it is shared space by a couple.

I have never had an issue with meal choices, and I board sometimes early and sometimes very late. Most DeltaOne flight attendants take meal orders shortly after handing you the menu at boarding. (so, boarding early is not a horrible idea if you are concerned about meal choice)

Be aware, (active) business class galley is behind row 9; and service is back to front. So row 2 is the last to be served. This is not an issue for me, since even on (short) Eastbound transatlantic flights, there are enough people who decline a meal (and just sleep) to offset the fact that I am being served last.

Since the front is not an active galley, and one of the toilets is nearer to the cockpit (with the sliding security door for that toilet when being used by the flight crew) there is very little noise from the front of the plane (and front galley area).