In some matchps the turn one Aether Vial is the scariest play that is most important to stop, in others the seven mana Karn Liberated, on all the various scary important spells to stop Force of Will offers you the best or near best odds on stopping it
Similarly, the card sees rather minimal play in Legacy, as its simply not needed for the best strategies
(When Summoned, its ATK becomes equal to the current ATK of the monster on the field that has the highest ATK
Necromancer is the strongest among the bunch because you get to immediately Special Summon whatever you've invested for his Summon, essentially making him a roundabout pseudo-Monster Reborn
Grabbing Summon: Yojimbo or Summon: Ixion when you need the removal that they offer is really strong
Kangee, Aerie Keeper Kangee, Aerie Keepers value hangs on how many feather counters it has, and thus how strong other fliers are beside it