Mutant champs to rank up
Hi I need some guidance and opinions on mutant champs please. I have a lot of mutant iso due to expire so need to rank up worthy champs. I'm in act 4 on last chapter and on heroic level comfortably. I have plenty of cat 3, 8 cat 4 basic but only 2 in mutant which really limits me. This rules out 5* champs at this time. Wolverine is good but is he still as good with new champs coming out, sabertooth and omega red I feel may need to be awakened first. Is Emma frost worth rank 5?? Is it worth ranking any three stars?? Thanks in advance for you thoughts.