http://www.naturalhorsetrim.com/boot_swap.htm

I bought 2 sets of boots off this page.  Decide which ones you want and check and see what's available.  I use the old mac originals, easy to put on and have never had one come off. 

When you say "horse boots", are you meaning hoof boots, or a support/splint boot? I assumed hoof boot at first, but a hoof boot really doesn't protect a horse's leg from injury, so I'm not certain.

I have kept my horses without shoes the last three years, and have managed to show at the APHA breed level, plus trail ride in fields and down the road. My horses are barefoot most of the time, but I use hoof boots when riding on the gravel roads. I use Easy Boots, mostly because they are available in my area. When I bought my first pair I had no idea what I was getting into - I knew no one that used them and simply went out on a limb and bought some. And in general I'm happy with them, they have lasted several seasons and have saved me from shoing my mare.

Picking the correct size isn't hard, simply draw around the bottom of your horse's hoof, and take that in with you when you're shopping. There is always a good description of the size on the bottom of the boot box. Also, if you go onto the company's websites they'll give you lots of info onthe topic. I have used the basic Easyboot, and they work well as long as I stay on hard, flat ground. I have pulled them off in soft dirt or mud before. Having said that, my basic pair is a bit large for my mare, and ideal size might stay on better. I also have two pairs of Easyboot Epics, this have a "gator" which basicaly is a split boot thingy attached to the basic boot. this does two things - it keeps them on much better, and it also stops your horse's hoof from bumping his leg and pulling off the boot or injuring himself. I have only pulled an Epic off once, and that was when my horse had a wreck, spun around super hard and spun right out of the boot. Then again, I haven't used the Epics in alot of soft mud or dirt either, because in cases like that I tend to just go barefoot.

The one bad thing about them (besides the price, which you can justify because you'll save money on shoeing with them) is putting them on and taking them off. Even after several years of using them i still find them a bit of a pain. Not too bad, but annoying. It only takes a few minutes extra to put on or off all four boots, but it does take a bit of twisting and force. It also takes the horses time to get used to the proceedure, my youngster tended to protest a bit at first. If I can get by without them, I do, because I really don't enjoy getting them on and off. But in general they are worth the money, and the hassle. Nothing is perfect, i wouldn't say these are either, but they do what i need.

I haven't tried Ol Mac, but i did try the Cavalero ones and returned them - they use velcro to fasten, which i don't think will last, plus they ride high enough on the horse's foot that they would rub the hair line. Easyboots only touch the hoof, so you don't have to worry about friction burns. Good luck, hopefully this helps a bit.

Buy the EasyBoot Bares.  They are very easy to put on and take off.

the first time I bought a EasyBoot Bare, I thought I'd never get it on the hoof. But last weekend they went on almost as fast as the EasyBoot gloves.  So they do loosen up and get easier with use.

The EasyBoot products as mention protect the hoof so you don't have to shoe for rough trails. they do nothing for leg protections. If you are looking for leg protection, Hoof boots are not what you want.

I have had great luck with the Renegades.