I have got both - a nuumed cc which is fab with the jumping flaps & a nuumed dressage square. I also have a WOW dressage square.
I prefer the velcro D ring tabs on the nuumed - the WOW square has leather bootlace things & I'm too lazy to tie them. The WOW square fits really well around the pommel / wither area. It is unlined so I can wash it hotter than the nuumed. Altho it's plenty long enough for the saddle from front to back, it isn't as long as the nuumed & I prefer a bigger square. All my stuff is large / fs.