Allen is the better QB, Mahomes is the more accomplished QB
It happened last year. The Chiefs and Mahomes haven't been the same since Bieniemy left; which sounds crazy but it's true. Kelce has lost a step but Rice is a very good WR1 but the team morphed into a running team and while they continue to win it's just a string of luck and an amazing defense. Their Defense took a step back though this year though (I think losing Sneed is hurting them). I'm not sure if it's because of the O-Line but their Offense is more about quick passes. I know teams are using the 2 shell defense against them meaning they should.... and that tells you a lot about Mahomes because teams are afraid to not play it.
I've said this before and I'll say it again: the only thing I think Mahomes is better than Allen at is his deep throw accuracy.