Hi jiqiangxia,
All the mattresses made by the same manufacturer would be in a similar “value” range based on the cost of materials so from a material point of view any of their mattresses would be “worth it”.
Having said that … the most important part of the “value” of a mattress purchase is how well it matches your specific needs and preferences in terms of PPP. No matter what the cost or quality of a mattress … if it’s not a good match for you and you don’t sleep well on it then it would have little value to you.
The biggest difference between the two mattresses is that with the Eurotop you can customize the mattress both before and after your purchase with a layer exchange if you need a softer or firmer comfort layer while with the Ultimate Dreams you can only choose the firmness of your comfort layer when you order it and you can’t change it after a purchase.
As you mentioned … a top layer that you can remove and replace also allows you to make changes to the mattress years down the road if you need to without having to replace the entire mattress.
Which one would be the best “value” for you would depend on the parts of your personal value equation that are most important to you and how confident you feel that the initial comfort choice you make will end up being the one that is best for you.
Both mattresses would make very good quality/value choices but one may be better “value” for you regardless of whether someone else may make a different choice because their criteria or confidence level was different from yours.
It depends on which type of latex, the size you are looking at, and where you buy it from but you can source the prices of a range of 3" latex layers in the component post here. Just as a single example … you can see Dreamfoam’s price for a 3" Talalay topper here.
Phoenix