I love this question! A piece of glass with lots of colors, contrasts, swirls that will come to life when you get that first hit..........I love that experience.  My first dedicated dmt bowl for changa was rainbow friz with a tight twist through the middle.......wish I had not broke it.  If you can make your own GVG and have the glass skills to mix and match colors and styles, I'd say go nuts and make them and test them repeatedly until you find the one that's perfect.