I am preparing to take mine to r4. A game changer as you already know, especially with the Nick Fury synergy.
With much of the endgame content in your rear view mirror, you'll eventually be looking to Abyss, I'd imagine. Human Torch is one of the most valuable champs for Abyss. However, all 3 are excellent choices. I'd say go for the one you enjoy the most (for me, that would also be Human Torch).
I am preparing to take mine to r4. A game changer as you already know, especially with the Nick Fury synergy. Yeah that NF synergy is pretty great. Sometimes I use a team of her, NF, CMM, and ghost. It’s lovely