I have tried tons of spring mattresses in store and many of them feel very different in terms of the springs, foam, etc.
I bought my mattresses from Foam Sweet Foam. Originally I had a queen with 3 layers (Top Layer: Talalay Medium, 2nd Layer: Dunlop Firm, Bottom Layer: Dunlop X-Firm). When I upgraded to a king, I got 4 layers and it is heavenly. The only bad thing is that they are a bit heavy. You can swap out different layers and do split layers as well. They also have a 120 night trial period.
https://www.foamsweetfoam.com/
https://www.foamsweetfoam.com/returns