Most mattresses I have seen in the market that are within my budget either are pocket springs or bonnell (inner) springs.
Pocket springs are springs that are not connected to each other so when your partner tosses and turns, you won't feel it. It's like the Simmons commercial with the bowling ball. Bonnell springs technology is less advanced than pocket springs. The springs are connected. Because of that, mattresses that have inner/bonnell springs are cheaper.
Full latex mattresses are just made with latex with no springs at all. However, nowadays, most brands have mattresses that have a layer of latex on top of pocket or inner springs. It's like a layer of comfort on top of support. Natural latex prevents the proliferation of many bacteria and has a proven anti-mold effect.
At the end of the day, you have to try the mattresses to see which one you feel most comfortable with.
Hope this helps.