If you want them to last, don't buy them. I had a pair of Horze a few years back, and they did not hold up to consistent use. Horze is a cheap brand in general, and I can almost guarantee these boots are made from artificial leather.
I'm not sure how much you will be using them, for me I wore them every time I rode, about 3-5 times a week at the time. Twice a day maximum, I only had 2 horses then. They were not terribly abused, I dusted them off after every week and cleaned them thoroughly about once every two weeks. Kept them as far away from water as I could. I will say they were incredibly thin, which works well if you need them to stretch.
I really don't have anything good to say about Horze boots, aside from them being cheap.
However, a boot I would recommend would definitely be a baseline Ariat field boot. Most local tack shops will carry them, and will probably have a good deal on them too. I have a pair of the Contour II field boots, got them for $200 at my local tack store. Great quality leather, thick but not too thick. They take a bit to break in, but once you do they're amazing.
If you wanted to go a bit further, I would recommend Tattini. They're my current favorite, so much so that I've sidelined my Ariats. Incredible quality leather, thinner than Ariat but easier to break in, and fits your leg amazingly. Mine have an elastic side panel that allows them to stretch a bit, as I have small ankles but semi big calves. They're beautiful and have held up wonderfully through all the wear and tear I've put them through, including waltzing through paddocks full of puddles. They retail for about $350-400, for the model I have at least (the boxer). However, I got a discount because my grandmother is one of their retailers. I'm sure you could snag a pair for $300.
This is all just my opinion, I'm sure others will have different opinions, and I encourage you to compare them and decide on what is best for you :)