A vaporizer is way more wasteful than a joint, no questions. The manufacturing for the electronics has a wildly greater environmental impact than even thousands of rolling papers, and the vaporizer will not work or last forever, so will likely end up in a landfill and replaced before long. I don't know what type of shortsighted environmentalist would ever look at a joint and go "that's contributing to trash". The waste products of it are literally entirely compostable.