Sources are conflicting, but the general consensus I've seen is that the Intel ME has direct access to your networking hardware, while the AMD PSP does not, and basically just exposes interfaces to the CPU.
If accurate, this is a significant functional difference as far as I'm concerned.
But, what's the old saying again? "The only truly secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards - and even then I have my doubts."
The PSP is still essential to the boot process and many probably other things (power management, etc), and you aren't going to just magically turn it off with a UEFI option. If your concern is that the PSP is a blackbox covert channel, it probably changes almost nothing.
Both AMD and Intel are functionally equivalent here, as far as I'm concerned.
(My ASRock X399 board also has this UEFI option and specifically calls out that it only disables a few key features.)