Hi Alimb,
You are certainly looking at some great options for your daughter and all of them would be in a suitable firmness range and none of them have any lower quality materials or weak links in their design so it will really come down to your own personal preferences and budget rather than a “better/worse” choice.
While I don’t have any personal experience with any of them so I can’t tell you what any of them would feel like for me much less for someone else … the Pure Echo would probably have a little more familiar “feel” for those that are used to sleeping on an innerspring and may have a little better edge support as well while both the SleepEZ Naturale and the Select Sleep 7000 would have more of the “feel” of an all latex mattress which some people would strongly prefer over an innerspring/natural fiber mattress. The Pure Echo would also be a little more breathable because of the innerspring but with the wool quilting on top of all of them it’s very unlikely that any of them would have any temperature regulation issues.
All of the mattresses you are considering use all natural materials so there is little to choose between them in terms of using natural materials. The Pure Echo uses natural wool and organic cotton and the Naturale uses 100% natural Dunlop along with natural wool and organic cotton and the Select Sleep 7000 uses 100% natural Dunlop and natural cotton and natural wool (although you would also have the choice of blended Talalay layers as well if you would prefer the feel of Talalay vs Dunlop).
The Pure Echo has a single firmness choice but since both sides would be the same firmness you can flip the mattress over so she can sleep on either side which would extend it’s useful life as long as you flip the mattress on a regular basis (see post #3 here). The Naturale has a firmer and a softer (medium) side so your daughter would probably have her favorite of the two and would probably only sleep on one side but the durability of latex would also compensate for the fact that she would probably only be sleeping on one side and the mattress can’t be flipped.
The Select Sleep 7000 would also have a firmer and a softer option (by rearranging the layers with either the firmer or softer layer on top) and would also be a very durable choice and it would also have the additional option of being able to fine tune the comfort and/or support of the mattress by exchanging one of the layers for a different type of latex or a softer or firmer layer and it also provides the option of replacing just a single layer of the mattress instead of the complete mattress if one of the layers softens or breaks down before the others (usually the top layer) or if her needs and preferences change down the road as she grows and reaches more adult proportions. It also has the additional pillows and sheets that go with the mattress.
All of these mattresses would also be a good base for a topper if your daughter needs some additional softness as she gets older as well.
Once you are down to a list of finalists and you are confident that they would all be a suitable for your daughter in terms of firmness and PPP (which they most likely would be) and that there are no lower quality materials or weak links in any of them in terms of durability (which there aren’t) then you would be down to finalists that are comparing “good to good”. If there are no clear winners between them at this point (which is usually a good indication that you have done some very good research) then you are in the fortunate position that any of them would likely make a good quality/value choice and (post #2 here) can help you make a final choice based on any preferences your daughter has shown, 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 fine tune the mattress or exchange or return the mattress or individual layers, 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. Sometimes a final choice may even come down to very minor differences or can sometimes just be a matter of “gut feel” or “educated best judgement”.
I’m looking forward to finding out what you end up deciding but you are in a great position that you really can’t go wrong with any of your choices.
Phoenix