In terms of lock strength:
AD10 > AD20 > AD15
In terms of ease of operations:
AD20 > AD15 > AD10
The Shark lock combine the best of strength and ease of operation.
According to Demko, AD20 is also much easier to manufacture than AD15, and AD15 was supposed to be easier to manufacture than AD10.
Finally, according to Demko, Shark lock is also designed to be modular where you can swap different blade to the same handle, or even swap a different handle shape with the same lock. because it doesn’t need crazy tolerance for the lock to work, unlike the Triad lock.
I still prefer the Triad lock the most. It’s the only design of the 3 that doesn’t need liners in the non-metal handle to be strong enough. This gives it the potential to have the highest strength to weight ratio. It’s hard to make knives like Airlite and Broken Skull with Scorpion or Shark lock.