I have a pair of Rimfrost mountain horse tall boots from Carousel Horse Mountain Horse Rimfrost Rider Tall Boot - Ladies
(which if you sign up for their newsletter you get 10% off coupon)
They are a pain to break in, as they are a synthetic material, but once you have them broke in, your golden - and they squeak with my synthetic english saddle, but they are amazing. I got size 9, and a wide calf -- I have never had a boot that fit my calf this well! You don't need to wear a thick sock with them to keep your feet warm. I have a crappy ankle and they give me good support on the ice and in the saddle. I have yet to find a stirrup they haven't fit into, and I ride in a handful of different dressage/AP saddles used by adult riders and have never had a problem with them in the boot going into the stirrup. They do feel pretty stiff when you use them in the saddle the first few times until you break them in.
I am from the wildly cold wisconsin - and I have survived thus far with them. I even used them for hiking and hunting where the ground was cold and uneven. They are pretty much my go to boot when going outside.
Oh, if you want to ever look up reviews and such, go to horsetackreview.com you can always find the good, the bad, and the ugly about things.