Mid-ship can be a bit smoother with less rocking and lower level cabins have less rocking as well. The back often has nice views, especially if the cabn faces to the back. Cabins that are quite low, in the back, can experience more engine vibration and noise related to docking in the middle od the night. I guess these are trade-offs, for the view of the wake.
In summary, the best location is on the ship period. Why worry about the details???