Next R2 6* advice
I'd like to some input on my next r2 6*. I don't factor synergies much into my rank up decisions, but they are a nice icing on the cake in this case. 
For SG, I have a r2 6* Venom that I love and use all the time. 
For the mutants, I have both Prof X and Apoc as r2 6*s which synergize very well with mutant teams. 
What's everyone's thoughts? Or should I wait for a better option?