The best value for you dollar when it comes to carpet padding is a combination rebond and memory foam 8lb pad with a moisture barrier. There are many different brands of this type of pad and it just depends on where you're shopping. The memory foam adds resiliency and the moisture barrier will prevent any spills from getting to your subfloor.
A step above that would be a full memory foam with antimicrobial, such as Healthier Choice. This is also a "green" choice because it is fully recyclable. The downside is, some people do not like the firmness of the pad. With a combination memory foam and rebond (recycled foam) you will get more of that squishy feeling under foot if that's more comfy to you.
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carpet pad advice - mix of memory and foam
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