RC aircraft six-axis gyro stabilization provides much faster correction of attitude displacement than a 3 axis system. In addition to the three pitch, roll, and yaw gyro sensors, three additional accelerometers are included that sense and automatically compensate for uncommanded movement (acceleration) in the three dimensions. Now our little quadcopter drone can automatically resist flipping and being blown about by sudden wind gusts (try flying a 3 axis quadcopter on a windy day to appreciate this).
Six axis stabilization also allows sensing of uncommanded sideslip during turns. Very sharp banked turns can now be easily achieved with a six axis quadcopter by simultaneously applying rudder and roll control. Such turns are extremely difficult to achieve with a three axis quadcopters.
Accidental crashes with the ground are much less common with a six axis quadcopter. When flying, sometimes we lose orientation and find our quadcopter quickly heading toward the ground. With a six axis quadcopter, all we need to do is let go of the pitch/roll control stick, and apply some throttle. The accelerometers will sense if the quadcopter is still in motion, and will automatically compensate to rapidly achieve steady hover.
Finally, the six sensors in combination can detect both unusual attitude (if we're flipped upside down) and can also tell if we're falling to the ground. By centering the pitch controls, and applying throttle, a 6 axis copter will quickly right itself and come to hover. This comes in handy if the quadcopter is flying uncomfortably high. Now it can be quickly and safely brought to a more comfortable altitude by simply cutting the throttle and letting it drop. It doesn't matter if the quadcopter tumbles during the drop. Just increase the throttle when it gets close to the ground. The quadcopter will quickly right itself and achieve hover. This last one is really cool and must be seen to be appreciated.
Six Axis WLToys V212 in Action
It's obvious that for most beginners a 6 axis quadcopter is the best option as it's most forgiving. It's even appreciated by more advanced flyers as a 6 axis quadcopter is also very nimble, able to "turn on a dime". Some excellent 6 axis beginner quads that I recommend that you might consider include the WLToys V202, and V212 quadcopters. Other's include the Hubsan X4, and the UDI U816. All are available at the best prices that you'll find at Banggood.com. However, please note that Banggood products come directly from China, so there will be a few weeks wait if ordered from them. But also note that Banggood does stand behind their products, and are more than willing to bend backwards to satisfy you if you have problems.