I ride all 3 - road, full suspension 26" mtn Flux and hard tail Kona Kula 29'er single speed. The 29'er is my go to bike for most all dirt rides, it's fast, light, fast handling and most importantly FUN!

I would recommend a 29'er, esp. if you've been riding road bikes with similar wheel size, it may feel more intuitive than smaller wheels. The larger wheels roll over obstacles better than 26", helping to smooth out the terrain. If you have the option for tubeless rims and tires, do that. You can run lower pressures (23- 25lbs) to soften the ride up a bit. Wider tires also help. Good luck!