There are a lot of options out there for your kitty's litter box. There is no wrong choice, and everyone has their preference. For kittens, I always suggest non-clumping litter. The biggest factor in this is that, kittens can be clumsy and messy! A kitten may stumble or misstep in the litter box and - whoops! - step right in their potty or poo.
So then what happens? Cats are pretty clean on instinct, so they go to clean that mess off of their foot...and then they've ingested the cat litter, along with the mess. Popularly used clay clumping cat litters are made to form a sticky, glue-like ball of clay when they get wet, to make for easy scooping clean-up. But, what happens when the litter clumps like that inside your kitten's stomach? Well, it can be very dangerous - to the point of requiring surgery! So I personally try to avoid that altogether, at least until kittens are older and less clumsy.
My preference for kitty litter is actually sold for horses! Pine Pellet Horse Bedding from Tractor Supply (or other similar feed stores) is what I use! It is around $6 for a 40 pound bag, which is a great price. As long as you don't have an allergy to pine, this is a great option!