If you ask me, this is a bit like asking whether it's better to get kicked in the teeth with a steel toed boot or tap shoes. These programs tend to rely on undocumented functions which will tend to be broken by security updates and other things, making for a never-ending cat and mouse game. And when you think about it, how much time do you really spend looking at the controls on any given window? Do you ever look at them for more than 5 seconds? Yes, the flat look on Windows 8 is rather uninspiring, but it has the benefit of helping reduce the amount of memory your system is using (for something you'll barely even take notice of).
Programs like Windowblinds just drives up memory use, increases the load on the GPU, and could lead to stability problems because they rely on features that are undocumented because they're not intended for widespread use and may change at any time and without notice. You're better off seeing the back of such programs.