Christophe LEMAITRE the first one

Well as a rule of thumb, if you’re tall and skinny and still run incredibly fast your technique can’t be that bad.
He’s making large strides but isn’t overstriding: The knee of his swing leg is already in front of his trunk at touchdown, which is one of the most important characteristics of proper sprinting.
Maybe hip height could be improved, but by far the most improvement will come from getting bigger and stronger.