In general, the kitten should feel firm and not mushy. Since cattery cats are socialized at an early age, the kitten should have an alert, friendly attitude and allow itself to be held. However, each kitten is individual and some are more outgoing than others. Don't neglect that sweet little kitten in the corner just because he is not as demonstrative as his littermate. Also, the attitude of kittens varies with their age.
All kittens go through a stage where toys are much more fun than people.
If you see a kitten who is a little younger than that, check the kitten's attitude by playing with it using a toy. As a general rule, we find boy kittens to be sweeter than girls. Despite what you may hear, boys are easy to care for. Make certain the boy is neutered as soon as your Veterinarian feels is safe and ask your Vet to remove all testicular material. If you choose a little girl, you will generally find the kitten to be a little smaller than the boy as well as a little more active.