Cold 1st floors – add radiant heat or insulate basement? – GreenBuildingAdvisor

We’ve got cold floors in the winter on the first floor of our 1.5 story cape in Central CT (Zone 5). The house is heated with two single zone mini splits on the each floor (and one in each bedroom upstairs) – replacing the oil fired hydronic baseboards (that are still in place). 

The concrete basement walls are uninsulated, and neither is the sill plate or band joist.

How much warmer would the basement have to be to have comfortable floors?

My wife wants me to add radiant floor heating (I’d likely get a air:water heat pump to heat it), but I’m wondering if I spray foam the sill plate & band joist, would that be enough? Or insulate / drywall the walls fully?

Thanks for the suggestions!