Hi Quentin,
The support layer of a mattress is not usually the weak link of a mattress and both a good quality polyfoam base layer and a good quality innerspring would be suitable and durable choices so the choice would really be a matter of personal preference and on which one is the best match for you in terms of PPP and your budget.
You can read a little more about an all latex mattress vs a latex polyfoam hybrid in post #2 here and an all latex mattress vs a latex innerspring hybrid in post #2 here.
I think that a latex/polyfoam hybrid would be more of a budget choice for people that can’t afford all latex while there are a number of people I know that are among the most knowledgeable in the industry and could choose any mattress they wanted and who sleep on a latex/innerspring hybrid so this would be even more of a preference choice than a budget choice (although an innerspring is typically lower cost than a latex support core). Everything boils down to PPP and your personal value equation because all of these can be good quality and durable mattresses.
Phoenix