Mr. Fantastic or Mr. Negative? Rankup

Doosra

Both are 6*s
Have a rankup1-2 gem from act 6 completion
Whom should I go with

Doosra

Both unduped

TheBlindSalmon

I would say take both eventually, as for who goes first, depends on what your roster needs more - get Fantastic if you need power control and heal reversal, Negative if you want a hard counter to degen. Negative is also trickier to play, so try them both out first if you haven't and see if you like the playstyle.