R4 Upgrade options

Jank39

Not yet started Variant 2 and don't really have too many viable champs for that so with that in mind...

Mathking13

Venom is amazing for variant 2. especially that last quest and how he just tears through everything. He's also a good counter against Spider-Gwen, which is very nice.
All three of those characters will be amazing for your roster, though. Havok just has a ton of damage on his sp3 which is really nice, and Archangel just minces through champs as long as they aren't bleed- or poison-immune. His awakened ability probably also helps the most out of those three options you have there. He's worth a generic imo. The others... well you only really should use class gems on them.

Don't forget though that this is just a game, and it really comes down to who you want. Don't feel forced to make rankup decisions just because people tell you they're better (like how I wouldn't take a stark spidey up just because I don't enjoy playing him that much).