Grounding boxes which ones have YOU tried? And results?

Just curious have never tried the many grounding devices that can be found on the web from companies such as: Synergistic Research, TELOS, Entreg, Nordost - QRT, Audio Magic -Blue Dot Eliminator, Signal Ground Solution or many DIY. Do they do what is claimed? Are they worth the $$ which are from a few hundred to many, many thousands! Which units have you tried/used and what were your results?