This card is very good for any hero that cares about attaching upgrades to minions. Air Cover enables a whole ton of synergies in the Aggression aspect alone, potentially more if you manage some kind of cross-aspect deck (for example with Spider-Woman, or playing campaigns that allow you to put cards from other aspects in your deck). Cyclops also has great synergy with it.
One of the best things about Air Cover is that it looks for the card in both the deck and discard, meaning you don't have to care where the attachment upgrade is whatsoever. This fixes a well-known issue of needing to have the attachment in your hand when a minion is on the board. Air Strike gives you the attachment at the exact time you need it and you have full control over what and when you do.
Currently, it pulls out Marked and Suppressing Fire from the Aggression Aspect. There's no Neutral upgrade that can be attached to a minion, but these two are already good enough. 2 allies and 3 attack events in Aggression have synergy with upgrades attached to minions.
Glob and Shark-Girl love them both equally. Same with Surprise Move and Coup de GrĂ¢ce, where the former is better suited to someone with high enough attack that can leverage readying well, while the latter is an outright insta-kill that can save you from some nasty 'When defeated' effects. Take That! will probably benefit more from the overkill dmg, as most minions don't have that much HP. If you don't care about the overkill dmg, you can always benefit from a little healing action. In all of these instances, there's a ton of synergy to be had with various other effects, such as damage buffs and excess dmg shenanigans, all enabled thanks to Air Cover.