Both are so good, and so similar. If people want to use resume and head to head as a tiebreaker and rank Mahomes ahead of Allen, I think that's very reasonable.
But he's not a better player than Allen. Period. Allen does things that no other QB in the league can do. Maybe no other QB ever.
Regardless who have a at 1 and 2, there is a MONSTER gap between these two and any other QB in the league. Brady and Rodgers ain't what they used to be. Allen/Mahomes are now in a tier of their own.