4* Champion Help Needed

Howdy!

I’m at a weird roster point right now. I’m getting to champion 4 stars, thus feeling the ISO pain.

Currently the following characters are at 13 covers:
Invisible Woman
Mr. Fantastic
TA Hulk
Jean Grey
Winter Soldier
Venom

I have a icon_mrfantastic.png
and a icon_invisiblewoman.png
dying on the vine (2 days left) with only enough ISO to champion one of them.

Looking for suggestions on whether to champion one of the two, or save the ISO for when another icon_hulkcho.png
or icon_jeangrey.png
cover comes along.

I do have 13 characters champ’d already, including Rhulk and 4clops, so I’m doing good there.

Thanks!

Invisible Woman is worth it, in my opinion. Her green hits hard and her yellow invisibility is one of my favorite powers in the game.