I think you should go for the black magic line of cameras, since they have amazing dynamic range so you can achieve amazing results when in resolve. But since you mentioned that you are not interested in the ursa mini, I would say for an affordable option you should go for the GH4, im not sure how the sony a7 series handles High dynamic range or if raw video can be achieved, but certainly they perform incredibly in low light.
That being said, if you do plan on using resolve also consider a colour accurate monitor if you do not have one already