LOWA GTX HUNTER EXTREME! Hands down, there is no other boot I have tried that even comes close. I put on 100's of miles in southern AZ chasing mountain lions in the heat. Sometimes 90 degrees, in rocky steep terrain. I know it is not designed as a hot weather boot, but you will not be dissapointed. They breath amazingly well, but the real key is how they hold your foot. I have never even been close to getting a blister. Two weeks ago we hiked in 85 degree weather for 20 miles with over 3000 vertical feet of climbing. Hiked almost nonstop from 5:15AM to 5:00 PM with a decent sized pack and video gear. I had no foot issues whatsoever!
They are a little pricey but they will last a long time. I have tried a lot of boots and under my use nothing has lasted for more than a month before something went wrong. These have gone over 2 months now and don't show any sign of falling apart soon.
LOWA Boots USA / Show Hunter GTX Extreme Boot