Pick of the litter 

explanation :
This idiom comes from the use of the word 'litter' to describe a group of kittens or puppies that has just been vorn.  A cat might have four kittens, and the 'pick of the litter' would be the best-looking, healthiest kitten.  The idiom is extended in everyday speech to mean the best of any group of things.  

e.g. Four new kids joined the baseball club this summer, but Todd was the pick of the litter.