Inov-8 is a scrappy British trail running shoe company which is equipping many of the top mountain runners worldwide, including the world champion John Wyatt of New Zealand. Even the recent Applachian Trail speed record breaker did the entire trail, all 2174 miles in 47 days in Inov-8's.
Why? A unique approach to getting the foot in a more level/neutral position to the ground for greater stability combined with wrap around ankle and arch support via the upper. I also like their product matrix which clearly differentiates different sole and shoe constructions for different terrains: mud, rock, grassy, mixed terrain thus going well beyond the usual breathable and waterproof uppers.