Between the two I would go with the ATPro. I’ve had both. The audio on the Pro is far superior. For example, deep clad dimes on the Pro are easy to hear. I dug almost 300 the year I ran the Pro. With the Max, those deep sounding dimes (with corresponding good ID) are tiny shards of canslaw. I followed up areas I hunted with the Max with my Vaquero and was surprised to see how many dimes it didn’t find.
That was my experience. I regretted selling the ATPro but not one regret about getting rid of the Max.