Go for temperament above all else. You've got a mix of breeds, so your chicks are going to be mixed breed birds. There are several threads about mixed breed birds, you can take a look and see if they appeal to you or not. Personally, I like them as I like having birds that don't look just like everyone else's.
If you want offspring that lay colored eggs, go with an Easter egger rooster, you'll probably get pullets that lay green eggs, and a variety of feather colors. If you like the looks of barred Rocks, get a Rock rooster. He'll throw mostly black, all barred chicks on those hens. Or, get something like a nice buff Orpington just to shake things up. You're not going to get any weird mutant looking bird by mixing breeds, just a variety of colors.