For what you describe as your preferences, I would probably recommend Summit. Although I am a little reluctant to recommend an older Celebrity ship.
Otherwise I would say Breakaway because its the newest (and I want to see it), but it also focuses heavily on specialty restaurants and entertainment.
For food & comfort it seems Celebrity outdoes Carnival or NCL, so Celebrity. I would like to see you on the Solstice class, however.
Also, I would recommend Explorer but since you are going on Oasis later that would make the explorer cruise less memorable for you after the fact. (if that makes any sense, it does to me, but I don't know if it does to you).
Are there any Holland America, Princess or (even better) Oceania or Azamara cruises going out then?