Who is better sig investment??

Hrishikesh713

So yesterday opened science nexus and awakened my 6* rank 3 overseer finally and today got mystic gem and as it is second mystic gem i got (one saved for rintrah ) i can use it on mojo or wait for Wiccan/classic sw/Spidey supreme ...i have also 6* rank 1 guardian awakened sig 20 (i mostly use 5* rank 5 sig 200 guardian of i have to use him sometime) and now i got like 100 sigs or Mr fantastic who is sig 60 ...so who would be better sig investment??? Considering Content and Battlegrounds....i do have other champs at high sig who really wants it except unawakened thing on whom i don't have gem to use on and will have to wait for void...!!!