Birds that I have found "Semi-feral" while still providing eggs/meat, AND are cold and heat hardy include
Barred Rocks and Wyandottes.
I don't think you can get a specific breed that "pretty much sustain itself" on any land. Predators come, and some predators are no match for chickens, even if they are semi-feral.
Some breeds are known to be aggressive, but I've found them to be sweet, and vice versa. The only way I could think to ENCOURAGE aggressiveness, would be
not to handle them as chicks, then
introduce lots of roosters when they grow up so they learn to fight each other and could therefore fight off predators better. Rooster fighting could probably cause some issues, but I think that's the only way to encourage fighting abilities.
Hens usually run to hide at the sight of a predator, so you would have to rely on roosters or other guard animals to protect your flock.
Good luck
I'll tag a few people I think might be able to help.
@TheOddOneOut
@Mrs. K
@Chookwagn
@U_Stormcrow
@aart