Hi tbizzle,
You may have read this already but post #2 here and the topics it links to also has much more information about mattresses and children and “safe” materials including a link to some general guidelines for children in post #2 here. It also includes a number of links to the better forum posts and topics about mattress and children as well which also include more information about many good options for children which may also be worth considering in a wide range of prices.
For younger children any mattress that uses materials that are “durable enough” (see post #4 here) that you would also consider to be “safe enough” and is in a medium firmness range or firmer would generally be a suitable choice for a child. The choice between them would really be more of a budget and preference choice than a “better/worse” choice. The question of “how safe is safe enough for me” is specific to each person or parent and their individual sensitivities, circumstances, criteria, beliefs, and lifestyle choices just like some people may choose an organic or even a vegan diet and would consider other diets to be “unsafe” for their children while other parents would be quite comfortable making different choices.
The Brooklyn Bedding BestMattressEver uses similar quality materials in terms of durability but they are more costly and it includes more latex in the comfort layers but either one of them would certainly make a suitable and durable choice for a child in a suitable firmness level.
You’ve probably read these already but just in case you haven’t … two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you (or your child) in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability, durability, and value.
When you are down to finalists that are all choices between “good and good” (which you are) and none of them have any lower quality materials or “weak links” in their design (which they don’t) and if there are no clear winners between them then you are in the fortunate position that either of them would likely be a good choice and post #2 here can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations with each of them, your confidence about PPP and the suitability of each one, their prices, your preferences, the options you have after a purchase to return or exchange the mattress, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
Phoenix