Asking about boots is like asking which truck is best to buy. You'll get a lot of opinions.
I have owned Kennetreks, Crispi and Zamberlans. Crispi is my boot of choice. I own 3 pairs now. Fit my foot perfectly in my normal size, very comfortable, lightweight, good support, good traction and rands for the rocks.
Prior to the Cripis, I bought a pair of Kennetrek Mtn Extreme's from a guy that didn't like the fit. They were basically new. They fit me Ok but try as I may, I couldn't get them to ever be "break in" comfortable. Kennetrek has a loyal following but you will also notice a lot of Kennetrek's for sale. They are very stiff for sure.
Zamberlans - weirdest fitting boot I have tried. I returned the first pair and tried another model and had the same problem. It's been 3-4 years since I tried them so I don't remember the exact fit issue but I'll never own another pair.