Yea, what JP said. All-day comfort since they're the only piece of gear you'll own that's in use before you leave the house until after you get home.
I've been taking pictures of my climbing boots for several years now, new, and then fully blown-out. I keep track of how long they last, what parts of the boot fails first and the plusses and minusses of that model. In seeking out a new pair, I try to find something better than the last pair, but at this point in time, 13 pairs later, I'm at an impasse. I feel with all my heart, that the ultimate tree climbing boot has yet to be developed. I've had some really good ones, and I understand what features rock my world, but 'really good' is as far as I've gotten.
I like, and will continue to use, mountain boots, mainly because of availability. Any one of us can find em at the local sporting goods stores. I can't mail order them because I need to put them on, test their fit, roll to test ankle support, twist them to feel lateral torsion and wear them to 'feel' the softness / hardness of the sole rubber.
I go through two to three pair a year - an expensive habit- but some day a GREAT boot will be developed and it'll utilize kevlar thread, or something and maybe I can get a full year out of them, which would make my wife (and me) very happy.
The images are of new boots. Upper left, no depth to the sole contour in front of the heel. Didn't make the cut. Upper right boot, the sole rubber was very firm, almost hard. Knew from experience that was not helpful. Bottom boot, the winner, that particular day. Good ankle support (extremely important in my case), nice rounded contour of the sole arch in front of the heel. Deep enough for that occasional spike application. Nice, medium-soft rubber compound, grippy on inclined limbs and really good for footlocking. The sole is molded around a fiberglass plate that goes toe-to-heel, allowing me to step into a tight V-crotch and not cup around and crush my foot from the sides.
This particular pair, the Salomon STF6 GTX, were good enough for me to feel like it raised my climbing ability a notch. Problem is, they only lasted 4 months. Regardless, I bought a second pair after I blew the first ones to shreds because they climbed so exceptionally well and were very comfortable after I abused them a couple weeks through wet and dry, and then put a gel-sole foot bed in em.
I moved onto a set of Vasques after that that were really good, but not really, REALLY good. They held up for 6 months, though, which is pretty good for me. Right now I'm back in Salomons, an expensive GoreTex model, but they've been much worse than I could have imagined, in a number of ways. I am less of a climber now than I was a pair ago. -TM-