Eruption is probably the most powerful spike in the game at 25%
I think I'm starting to see a little bit of the potential of Aether Wave, Ike's Aether3. I used it before when I wasn't as familiar with Ike's combo game and was disappointed with the damage, but this supplements it quite well, especially with QD2. The other aethers aren't as great at damage racking as I thought because of rage (well, aether1 anyways). It is quite safe when used above someone, and excels if it's used against someone sent above a platform since it lands almost automatically. This is definitely a great tool on stages with platforms that are above the height of Battlefield's side platforms. The chip damage adds up when you use it conservatively, making it rival the 1-2 times you'll be able to hit with the other aethers. On the ground, the ideal height is slightly beyond ftilt reach, giving Ike a great tool at range without having to run up to them.
I mentioned this before, but the initial hitbox reaches out a bit farther than the other aethers and it retains some super armor even after landing for some reason. The projectile also has shield destroying properties and counts as physical (can't be reflected in any way).
It's vertical recovery is almost as good as Aether1's, but the horizontal recovery is poor. If you're hit out of your double jump, you're in extreme danger. On the other hand, it's much quicker and can still be reversed if you're hugging the side of the stage (be careful, though) and reverse aether hits quite easily, and it's more difficult to gimp once you're in position. Because you can grab the ledge quicker, you may acquire an extra chance to attack the opponent during his recovery.
Aether1: Bigger guys and attacking deep offstage
Aether2: Best mix of offense + recovery. You can't go deep, but you can go far out horizontally
Aether3: Least amount of damage, but most spammable and can go nearly as deep.