For all out, one of the newer aluminum castings. The best between the OEM castings? Shaft mounted rockers or stud mounted. Shaft is more stable. Closed or open chambers? Pretty sure there are available pistons that can help the open chamber. In the end, I wouldn’t sink a dime into a cast iron head if I wasn’t required to.
Both of the mentioned heads are closed chambers, each with either shaft or stud mounted lifters-they are price comparable entry level when replacing heads on a SBM.