We have been where you are. We explored every possible system, and every variant. Nothing was perfect, and most are either labor or money intensive. Our first building was a tank house for the water flow and equipment of an artesian well. It was a 16' inner diameter scoria bag catenary dome, with 3" of shotcrete inside and out. It has no windows and one door with a small window. The walls are about 18" thick, and it is significantly earth bermed on the back side. With only the additional heat of 4 light bulbs, it has sailed through Colorado winters without freezing. We are very pleased with the performance, but would not want to live in even a complex of them. Too closed in feeling.
We are in the permitting phase of a guest house made from a post and beam system with Hogan brackets. http://www.ezhogan.com/
We chose this system because it allows us to do a lot of the work ourselves, and we are leery of many aspects of someone else building our house. We will wrap the building in Faswall blocks. http://faswall.com
This is a high mass ICF system. It costs way more than I wanted to spend, but with the addition of some roxul insulation and lime plaster to the outside, we will have a reasonably well performing building with vapor permeable walls. http://www.roxul.com
Not super fantastic like I wanted, but reasonable.
We have limitations. We are around 60 years old, and have been waiting 10 years to find the right piece of land and figure out what we want to build. We live in a high wind and cold winter/hot summer area. Time's awastin'. If we had more time, I would probably lobby for a double wall earthbag system - earthbags ( or poured earth walls or cob) insulated by perlite bags. We talked extensively about modifying the Hogan frame to help hold the bags in place. I think we could have worked it out in a fashion similar to this eco-beam system. http://earthbagbuilding.com/articles/eco-beam.htm
I wish you luck on your project. If you really want to compare the mass benefits of different wall systems, some basic wall weight calculations will be helpful. You are definitely on the right track. Mass with appropriate insulation for your climate is where it's at. Our main house project with be Faswall blocks also, and though I don't like all the concrete it will take, we are building a 500 year house that will house our descendants for several generations if they can get their heads out of their phones long enough to learn how to grow food.