There is nothing to compare. Luffy split the sky with the strongest living being. He is above Big Mom. Kid has to 2 v. 1 Big Mom.
Who knows what happens with Big Mom and these 2. All we know is Kid has a larger played up relevance this arc than Law. He's tied back to the smile plot because of Killer. He has actual stake in beating a Yonko because he has the same drive as Luffy.
We can't really say anything about Kid yet because we have to see how Big Mom is handled next. If Law goes down, and it becomes a 1v1, then its justifiable to say that Luffy and Kid are still rivals.
But again, hopefully you'll understand that what I'm saying is purely guesswork. There are things that support it though. Law doesn't need to beat BM to find out about the Will of D. Kid NEEDS to beat BM to continue being in the running for PK against Luffy.