The most honest answer is, "it doesn't matter." These are very thin materials; we're probably talking about a difference in the number of watts/BTUs that can be counted on two hands, or pennies/Euro cents per year on your gas bill. It's background noise, unless you're talking about a floor of tens of thousands of square feet, in which case you're probably running a business and should have this calculation done by a professional.

The most honest answer is, "it doesn't matter." Assuming the worst case scenario that there is no insulation of any sort beneath the pipes, a flooring material with a lower thermal conductivity will cause a small amount of the heat to be directed downwards rather than upwards, but we're probably talking about a difference in the number of watts/BTUs that can be counted on two hands, for the cost of pennies/Euro cents per year on your gas bill. It's background noise, unless you're talking about a floor of tens of thousands of square feet, in which case you're probably running a business and should have this calculation done by a professional.