If the Price is not much more...Go with AB...The Aft Suites are very nice!!
Take a tour at this site of AA,AB,AC Suites
Have seen the AC on the side of the Sun Class ships, and had a AA on the Dawn Princess, with friends next door in a AB. AC on the side of the ship are more of a 2-room 'feel', wider, but the aft ones (my preference) are longer.
We sailed in C744 (cat AB) on the Sun Princess thru the Panama Canal and it was a wonderful cabin. We had sailed previously in an AC on the Dawn Princess and the aft AB cabin was definitely much nicer. Go for it and enjoy!