It all depends on what you plan on doing with the farm.
Each girl does something diffrent on your farm
EDIT:
Here, I got you a list of what your wife does on the farm (
Where I got it from)
Quote:
How Your Wife Helps Out:
Ann - Feeds the chickens and collect eggs.
Karen - Collects eggs, sometimes breaking them.
Popuri - Waters crops and collects eggs.
Elli - Collects eggs, and sometimes feeds chickens.
Maria - Helps with removing weeds and collects eggs.
They all collect the eggs. I think then they are automatically sold. I'm not sure.
They all take a load off, and knowing what it is they do can help alter your schedule. So with Ann, you don't even need to enter the chicken coop. And with Maria, you don't waste time and energy on weeds.
Karen is hard to win over (without a certain glitch), but does next to nothing compared to the others.
If you don't want to get chickens, Karen and Elli aren't right for you.
I personally chose Popuri.
However Maria is a good one, if you have chickens or not.