Correct me if I’m wrong, but surprisingly, ASM#1 was valued more than AF15 for a period of time.
The Af15 and Asm1 situation reminds me of The Wonder Woman keys:
All Star #8 -her first appearance. Worth the most.
Sensation Comics #1 her second appearance and first cover appearance. Considered the scarcest of the three and possibly undervalued.
Wonder Woman #1 Her 10th appearance, first solo book, it’s value situationally competes with Sensation #1.
The debut titles Amazing Spider-Man, Superman, Batman, Wonder Woman, and even Iron Man just command appeal!
I always thought the 1968 solo starts of Captain America, Doctor Strange, and Hulk would be valued more (and just feel/look cooler) if they were proper #1s.