Which mutant to rank up?

Cloud99999

I have the 4 stars of:4/40 rogue sig 21, 4/40 x-23 sig 20, 3/30 sabretooth unawakened that I pulled today from phc, 5* x-23 at 1/25 unawakened. I can max out any of the 4 stars or bring 5* x-23 two ranks up. Im planning on beating the collector within 2 months.