They aren't the same in essence and definately not the same in power, speed and size.
One uses natural lightning and the other uses elemental chakra.
If both attacks were to be executed on separate targets, Kirin would have the better outcome. If they were to go up against each other being used at the same time...Kirin would hit first. We can't put in another jutsu to be used to avoid Kirin.
BUT Raikiri is a better choice because of it's reliability, chakra usage, and the fact that it doesn't need prior requirements (other than chakra) to be intitiated...
This topic should have ended a long time ago. Before you know what came along.