Super flex Keeper Advice

My Super Flex league allows 3 keepers. I’m already keeping Terry McLauren in the 5th and Antonio Gibson in the 8th. Should I keep Raheem Mostert in the 10th and get 2 new QBs, or keep Kirk Cousins in the 16th?

I think I would keep cousins. Even as a third qb that’s huge value. Mostert in 10th is nice but ability to get another two qb and still have cousins costing nothing is too much for me