Hi JeanneS,
Any type or blend of latex (either Dunlop or Talalay and made with synthetic rubber, natural rubber, or a blend of both) is a high quality and durable material so the choice between them would be more of a preference and a budget choice rather than a “better/worse” choice. There is more about the different types and blends of latex in post #6 here and more about how Dunlop compares to Talalay in general in post #7 here but the best way to know which type or blend of latex you tend to prefer will be based on your own testing or your own personal experience.
Every layer and component in a mattress including the cover and any quilting layers will have some effect on the feel and performance of every other layer and component both above and below it and on the mattress “as a whole” so the overall design of a mattress and whether it’s a good “match” for you in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) is much more important than the thickness of any specific layer or layers which is only one of many variables that can affect how well a mattress works for you.
The only way to know for certain whether any mattress will be a good “match” for your specific body type and sleeping style will be based on your own personal experience.
There are also some comments about the pros and cons of each of them in post #2 here that may be helpful.
Either one of them would certainly make a great quality/value choice .
Phoenix