Hey there Markus,
I see no one's jumped in on your thread so allow me!
I hate to be the 'it depends' guy, but... =)
Any of those systems provide enough thermal mass to effectively cool a house in summer and keep it warm in winter. Integrating that wall style with passive solar design, appropriate tech heating/cooling systems and other elements of house design can create a home that is comfortable year round.
Which is most appropriate for your specific area depends on some other factors. How humid is the region? How wet are the soils? How much rainfall? Water plays a big part in the long term health and efficiency of walls. Also what's the elevation? How much wind reaches the site? Is it from a consistent direction, or is it more seasonal?
Rammed earth is traditionally seen in more arid circumstances, though there are notable exceptions to that rule. They're great for absorbing the heat throughout the day, and releasing it throughout cold desert nights.
Cob and strawbale are more universal in their use, though it's my understanding that straw bale is a little more common in temperate situations (where straw is more abundant/readily available).
There are a number of other strategies that are very helpful to keeping a home cool in the hotter parts of the world:
- Move heat sources outside. An outdoor/detached kitchen, shower, and laundry facilities help to prevent you from heating up the house you're trying to cool.
- Build to where the wind blows. Catching a cool breeze can make a huge difference in a home's comfort, and building with the direction of the prevailing wind in mind can mean a one-time action with benefits for years.
- Get low. This one is very dependent on your soils, but as we see in Paul's WOFATI building style, sinking a home a few feet into the earth can greatly contribute to the coolness and temperature regulation of a structure.
- Grow your house. Integrating plant systems, especially when paired with your ventilation system, can cool a structure significantly, while providing clean refreshing air at the same time.
- Cool in, hot out. Speaking of ventilation, being intentional about how air moves through the structure can help keep temps low. Venting hot air from the top of a structure, and using that movement to pull in cool air from near or even under the ground (using the Bernoulli effect) can continually cool your house, using the energy of the heat that you're expelling.
- Shade. Shading your roof and walls, either with plants or nonliving shade materials, can reduce the amount of heat energy entering a structure.
I know this didn't directly answer your question, but I hope it was helpful!