Looking through this thread and seeing some arguing regarding Killer Frost/Captain Cold, and makes me wonder why we can't just have both. NRS managed to make Sub-Zero and Cyber Sub-Zero play completely differently, and storywise they were the same dude. I'm sure they could make Killer Frost and Captain Cold play completely differently (especially now that the Injustice comic shows this universe is using the gun version of Cold). After all, they managed to make Joker and Harley play differently even though they are both psycho gun-toting gadget-using clowns.
Some people have said that two ice characters is too much, but I disagree. Ice manipulation is a very versatile power and there is plenty of potential for uniqueness. Killer Frost in particular, since she can make all kinds of constructs making stuff like ice pillars/shields to defend herself from projectiles, or tossing ice boulders/shards at an opponent, or creating spiked ice gauntlets to increase her hand-to-hand damage, or coating her body in a layer of ice to reduce damage taken, etc. They could get really creative with her. It's practically "Green Lantern ring"-levels of potential.