Your looking at several things, and the final answer is a compromise between all of them.
The smaller the shot, the more pellets, but the lower the penetration each one has (at any distance).
The tighter the choke, the further out you can hold a dense pattern, with all shot sizes.
The "tougher" the target (IE deer VS rabbit), the more penetration AND hit count you need.

So, what is the target, what is the distance, how are you choked?
BTW, for in house usage, you really don't need anything more than #9 target loads (at in-house distances everything including the wad will be inside a 1" hole), but you won't be punching through walls and endangering any family members on the other side