Hi shiftdelete,
The differences between them would be in the types and blend of latex they have available, the firmness of the layers, the amount of latex in each one (two of them have 12" of latex and one has 9" of latex although you can also add an additional 3" topper), the number of layers that can be rearranged or exchanged to customize the mattress either before or after a purchase, and any differences between the covers. There is more about the most important parts of a mattress purchase in post #13 here that can help you make more meaningful comparisons between mattresses.
There is also more about the pros and cons of thicker mattresses or mattresses that have more layers and options to customize the mattress in post #14 here.
You can see the return/exchange policy for for SleepEZ here and for Brooklyn Bedding here so you can compare them and decide which one would be “best for you”.
All of the mattresses you are considering use latex from top to bottom and have a wool quilted cotton cover so none of them have any weak links in their design. When you are down to final choices between “good and good” and there are no clear winners between them then your final choice (see post #2 here) will be a matter of “best judgement” based on how you feel after your conversations with each of them and on all the objective, subjective, and intangible parts of your personal value equation that are most important to you.
The tutorial post includes this link that lists the online members of this site that make latex mattresses and there are some others listed there that also make component latex mattresses that are in a similar budget range.
Phoenix