Hi jm20w,
The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how to avoid the worst ones.
Outside of testing a mattress for PPP (Posture and alignment, Pressure relief, and Personal preferences) … a mattress is only as good as its construction and the quality of the materials inside it and without knowing this you would be making a high risk and completely blind purchase in terms of quality/durability.
While I would normally avoid the major brands or any mattress where you don’t know the quality of the materials and components (see the guidelines here) … if you are considering a mattress that they make then at the very least I would want to know the quality of all the layers in the mattress to be able to identify any possible weak links in the mattress and make meaningful comparisons with other mattresses.
If you can find out the density of all the polyfoam layers in both mattresses (which is unlikely … see here) … I’d be happy to make some comments about either or both of them but without this I would avoid both of these or any mattress that uses more than about an inch or so of either low quality materials or materials where you don’t know the quality/density so you aren’t taking the much higher risk of making a completely blind purchase.
Phoenix