If you want to waste your youth away and mature overnite into a trendy old spandex snob, and eat gu, and measure proteins, complain, and drive in the slow lane, and record every thought and image that passes your mind onto a website, and only shop at 'one' shop, then go for the 29er.
If you think you ever plan on being a normal kid and try to get the wheels off the ground, ride dh, ride stunts, and eat candy bars, have a date for prom, and skid down the trail, and believe in santa, and be cool, make good videos, then get a 26er.
Hope that helps. 😀