Hi PBAB,
The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines that can help you make the best quality/value choices … and avoid the worst ones.
Unfortunately neither of the mattresses you mentioned include the specific information you would need about the quality/density of all the layers in the mattress and I would tend to avoid both of them.
At the very least I would want to know the thickness and density of all the polyfoam (which includes "biofoam) or memory foam layers and the type and blend of any latex in both mattresses. Without this information you would be making a blind purchase and would have no way to identify any weak links in either mattress or make meaningful comparisons to other mattresses.
It’s usually very difficult (if not impossible) to get the information you would need from both of these manufacturers to make an informed purchase (see this article) which is among the reasons I would tend to avoid both of them.
Phoenix