Which infinity stone is the best overall for combat considering both strength and versatility for its user to defeat another user with a different stone.
(insert Abstract or Omnipotent Being here) Creates 6 identical thanos and gives each an infinity stone. to differentiate them they were called Power Thanos, Mind Thanos, Reality Thanos, Space Thanos, Time Thanos, Soul Thanos, who all all identical but each has a different stone.
all individual stone feats allowed. no feats of stones used in combination
the goal for each is to destroy the other users using only the stone they possess.
no gathering or destroying stones. only users can be destroyed.
the universe is the location with a starting point being earth.
These thanos are in character with exception of following the rules