AKAV8R
FNG
After owning/training three working line German Shepherds (Czech and East DDR) kept as family protection dogs in remote Alaska, there is my vote. Absolutely fearless against anything I've met, man or beast, including 1,000 lb Brown bears. Whatever you do, do NOT tie one outside for even short duration in bear country. They seem to take pleasure in killing dogs on cable runs. Not mine thankfully, but I've seen several. My pregnant female import from the Czech Border Patrol kennel was especially impressive on Brown bears even solo. Breeder Yiri Novotny stated the dog had never seen a bear but surmised that bears and dogs have been mortal enemies for centuries. Makes sense, having seen wolves kill youngish Brown Bears on multiple occasions.
