Firstly, lets dispel some myths :)
Kittens do 3 things....eat, sleep, play,,,repeat! This means that if you visit to choose a kitten and you are looking for a playful one, a sleepy one etc then remember that if you came back two hours later then different kittens will be playing or sleeping than now!
It is the skill of the pedigree breeder to breed kittens the SAME, in that they should all have nice temperament. Normally, you are also choosing from the same litter with the same parents and the same genes.
Thats being said, they can and often do have their own personalities. Boys typically are a little bigger and a little more cocky and confident. Girls are a little smaller and often a little more reserved. This is also true of adults, and though not written in stone, I would always recommend a boy for a busy household especially if you want to show him off to visitors.
It can also depend on how they were raised, how many were in the litter and the mix of sexes. But they all grow up and grow out of kitten politics. If you get them on their own, they will al play, whereas in a group one may dominate the toy. If one has just eaten a big belly of food then its quite likely to be sleepy and lethargic....and kittens do have nap times....just like kindy kids :)
That being said, there are connections made that cant be explained, sometimes one just jumps out and you know its the one for you, sometimes its almost like the kitten chooses the person. Just remember, don't overthink it though, from the right breeder, there is no bad choice.