Hi sugbug,
Both of these mattresses use good quality materials and have no obvious weak links.
In general … when you are looking at an online purchase it’s usually best to go with the guidance of a knowledgeable and experienced manufacturer who generally know their mattresses better than anyone and are in the best position to help you choose a mattress that has the highest possible odds of being a suitable choice based on the “averages” of their customers that are similar to you in terms of body type and sleeping style (see mattress firmness/comfort levels in post #2 here).
The Astoria also uses the Tempurpedic Rhapsody Breeze as a reference point for comfort and support so you can test the Rhapsody Breeze as a reference point.
They are also a member of this site which means that I believe they are among the manufacturers that compete well with the best in the industry and they also have a great return policy so you can use your own personal sleeping experience to make sure the mattress they suggest is a good choice in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). NOTE ADDED: Restava is no longer a member here since a redesign of their mattresses and they may no longer be fully transparent about the materials in their mattresses … see this topic.
Phoenix