Roster Help Day 759

I'm currently a 3* -> 4* transition player, banking 90k ISO and have no clear plan on what I should spend it on. On the PVE side of the game, my roster is already strong enough to consistently hit progression. On the PVP side, I'm at the point where I'm fighting against championed 4* teams and can hit 1k with effort and shields, but choose not to in order to save shields for the 4*s that matter the most. I have other plans for which 4*s I want to champion next (Thor), but those covers have not come yet.

I currently have these covers for potential 3* champions, but have very little incentive to do so since they're either characters I do not use, give 4*s I don't need or want, while the 3*s I do want to champion eventually (IF, KK, Cyclops) drop covers at a slow rate:

-She-Hulk 3x (earliest expires in 3 days)
-Ragnarok (expires in 3 days)
- Sentry (7 days)
-Falcon 2x (8 days)
-Beast (9 days)

So, which ones of these would you say would be the least unhelpful for my roster in terms of use in pve/pvp/rewards and would be worth using for more than just the champion token? I will end up having to sell some of these covers before they expire, but I will also consider the possibility of selling all of them and hoarding even more ISO for 4*s if necessary.