have Samsung 6400 40", good.
Active shutter glasses are able to display more detail to each eye — the alternating-frame technology means a full 1080p image is shown to each eye, rather than the half frame (alternating lines down the TV screen) that passive 3D shows. This means that the video will have cleaner lines, especially on curves and edges. If high quality video is crucially important to you, active 3D is the choice to make. (You could just watch the movie in 2D and have the best picture, but that's another story.)
http://www.pcworld.idg.com.au/article/389806/active_vs_passive_3d_what_better_/