I currently have a mixed Motiv/Storm arsenal. They both put out very good equipment that you can build a company specific arsenal around. I have sanctioned 800/300's using both brands, and I'd be comfortable focusing exclusively on either one.
I do like that Storm is much more specific about how to closely reproduce their NIB finishes. In the area of published technical support, they seem to do a better job. Also, right now, my opinion is that Storm has a better selection of mid-range solid reactive (non-pearl) equipment. That may or may not be an issue for you, but just be aware.
At a nuts-and-bolts level, Motiv balls look better, and Storm balls smell better. Flip a coin and pick your poison.