They are both excellent. I prefer Lutron and they also happen to offer what are in my opinion the finest motorized shades in the industry, which are called "QED". They are dead silent, and use only low voltage wiring so it will be easier to retrofit them (infinitely easier if you live in an area where high voltage would require conduit), compared to shades which require high voltage wiring. Last but not least, all your wall keypads would completely match for both your lighting and shading controls. That could theoretically be done with Vantage too by using all Vantage keypads and interfacing to other manufacturers shades but the Lutron solution is extremely elegant.
There is a lot of good info on the shades on Lutron's web site.
There is a lot of good info on the shades on Lutron's web site.