The choice is ultimately yours....and it's sometimes a hard one.
I personally choose the one I want to play with, usually based on looks hehe! The one I want to see what happens with, what their children might look like.
When the time comes, just scroll through the adoption papers (click 'try again' a number of times) and see what their job is, what they look like now they are grown, and one might pop out at you as the one you want to play with next
