Hi Ricool,
If you follow the steps in the tutorial post here you will have the highest chances of success. It has all the most important information, steps, and guidelines you will need all in one place.
The choice of materials is always a matter of preference based on your own testing. Every material has higher quality and more durable versions and lower quality and less durable versions. While latex is a great material, it’s not everyone’s preference and I would keep an open mind and use your testing and personal experience to decide which type of mattress and materials you tend to prefer.
There are also no specific mattresses that are better or worse for back issues as a group and I would be very cautious about using someone else’s experience as a guideline for your own choice (see post #13 here). A mattress that works great for one person’s back issues may turn out to be completely unsuitable for you to sleep on. Your own testing using the testing guidelines in the tutorial post is the most effective way to decide which mattress is the best “match” for you and your back issues in terms of PPP.
If you let me know your city or zip code I’d also be happy to let you know of any of the better options or possibilities I’m aware of in your general area.
Phoenix