You can't beat Woof Wear Club boots IMO. We use a lot of different ones at work (livery/ event yard/ RS) and these are the easiest to use, toughest etc. etc. (I could go on!)
I like the WW double velcro ones. You can also pick up cheaper ones which are just as good off ebay. I have a cheap set which I use for hacking & lunging, they have had a lot of use in the 20 months I have had them and they are still in perfect condition (my horse does not brush though).
World Beater brushing boots are a very good cheap boot.
Very robust.. (neoprene with a suedette striking pad, with a put thru pull back velcro closure system..)
I like them because they are quite elastic and act like a support bandage too, and to date have never come off.. hunting, hacking, etc..
They are a very handy boot to have..I would'nt be without a set..
A Good "Workmans" Boot..