Are you talking hoof boots, or leg boots? I've never used hoof boots. Never felt the need to. I haven't had any horses with abscesed/punctured hooves or anything of the sort that would need extra protection for the sole of the foot.
I do, however, use sports boots. I used to use splint boots alone, but found that even if they were well adjusted, it was hard to find a good brand that didn't slide at least a little bit from where they were initially placed. Plus, they don't really prodive protection for the fetlock and pastern. I like the Professional Choice brand combo boots personally. I only use them on the front, though all four legs just adds more safety. I do reining and my first concern is striking their forelegs with the opposing leg while spinning or doing rollbacks.