Kydex beats the fabric in the uglies department and are hard and uncomfortable.
I dont really care about "ugly", as I carry IWB and no one sees it. Kydex is hard, but really no harder than thick/stiff leather, which is where a leather holster should basically be. Uncomfortable? Not at all, and if anything, much more comfortable in some circumstances.
Horsehide. No one sweats any more than I do, and sweat never penetrates to the inside of my holster. I take my Gun out at night, and by the next morning the holster is dry on the outside.
I suppose some of us might sweat a "little" more than others. What you do for a living and where you do it can also have a big impact on what goes on too. I work outside year round, and summers here are in the upper 90's with very high humidity. Im usually soaking wet from sweat by 9am most days, and stay that way for the rest of the day in the summer and early fall.
The last couple of years before I found Blade Tech kydex holsters, I used to rotate through two Galco Royal Guard horsehide holsters each summer, usually chucking one at the end of the summer. They were usually both constantly wet and soaked through the whole time too. Once soaked, they do not dry out over night, or even in a couple of days. I even tried duct taping, and sealing the side against my body, with no good result.
After switching to kydex, the only part of my gun to get wet and ever show signs of rust again, was around the left/inboard grip panel, the only spot the sweat guard didnt protect. Pretty much instant satisfaction with that first holster. I used that holster everyday too, for over the next ten years and still have it. Its well worn, and a small piece of the sweat guard broke off at some point, but its still as serviceable as the day I bought it. Doing the math, over ten years, that one Blade Tech holster saved me a bunch of money too. $55 for ten plus years, vs $140 +/- a year (or around $1400 for ten years), for the Galcos.