I like the tyres recycling possibilities very much. It seems the best way to recycle and build resistant houses' foundations in areas where earthquakes are common
Dude the tires is amazing I can tell you it's 20 minutes per tire pounding dirt. My friends dad built one. In Mexico we have very cheap labor so if you pay by the tire like a dollar a tire you will get your house built and a very large one built for a couple thousand. For a few hundred per wall spray on stucco for a nice finish and protect against offgassing.
My other favorites on the list are Expandable Chinese Shipping Container homes that slide out in both directions. You can get a set of 2 houses for 5,000 USD and each one is 15 ft by 20 ft roughly. Shipping was about 1500 or so.
Also I like Cob 3d dirt printing. I also dedicated an entire section to aircrete and i can see it being mixed with flyash(which is recycled). You can mix with hemp for ultra strength. The aircrete was so inspirational that I bought the machine and have had long talks with the guy from Gibran center.
Compressed earth bricks are great but they need to cure for a few weeks. Unless you buy the very expensive horizontal press and those can and should be dry stacked because they are uniform height. Interlocking bricks is a gimmick use rebar instead. I think if you've got 20k the horizontal press pays for itself. I think that is the one that makes uniform bricks.
Earth bags are good but getting those very long bags is actually hard to find and not as cheap as it looks. It requires a little research.
But those are some of the best ones. However they are all so exciting and this research will take me a year to finish.
I'm trying to find a clear "winner". Tires is definitely up near the top. But CEB 3d printing Aircrete Cob and inflatable forms are also very interesting.
Dirt homes have the best advantages for insulation being resistant to pests and being free and locally sourced. Which also makes underground options interesting if a flooding technique is found that is cheap.
This is where money comes into existence: it would be good if the Bitbay decentralized marketplace started to be used as a way to let these things happen. Wouldn't it be awesome?
By the way, I've started studying how to build eco-buildings from scratch. Yurt is my favorite so far...