Clean, not gasping for air. Look for the perkiest ones. I like friendly, so if they seem less afraid, awesome! There are some breeds that come right to your hand, like the golden laced Cochin, but they are not good layers. My Cochin has been broody 2 times already and she's only 9 months old.lol
I like Easter Eggers, sold as Americana's, rhode island reds are my favorite layers in my flock. I want a dark layer like a welsummer or maran, but that will be next time.
I hand raised my chickens and handled them daily, they are people lovers, but all very friendly breeds. It depends what your looking for in a breed. Friendliness is important for me. I have them as pets first, eggs second. I also love the different colored eggs. Here is a pack of my eggs. The tiny one if from my d'uccle. She's so sweet.
I bought my chicks locally. The farm store owner will put in a special order if your looking for a specific breed, which I thought was awesome. He says he sells chicks all year round. His biggest selection is in the spring, no minimium order.