Agreed with both.
It should not be depend on the amount of hits.
This is not working for inactive realms.
If it depends on damage though, I think it will come down to the same as before since you can calculate the damage reasonably well and the big hitters have an advantage.

I would be totally fine with a random lottery- one round system.
Why hit him over and over again anyway since it is determined before the animations of final round are done.