It also depends on the plane. I'll take 17A on a 777 before I take 30A as an example.

Lets see:
777: 17A (or the first row behind the crew rest on the XI) over 30A
747: Exit Row over anything. Of course it's quite a long wait for food if your at the second exit row
Ted: Exit Row over anything
A320(or A312): 6A is good as long as the cutout exists
etc