When selecting a 250cc ATV, prioritize the engine type (typically 4-stroke, air or water-cooled) for reliability. Check the transmission system, choosing between CVT (Automatic) for ease of use or Manual/Semi-automatic for better torque control. Ensure the suspension system features adjustable shocks and independent double A-arms to handle rugged terrain. Additionally, verify the braking system, specifically looking for front and rear hydraulic disc brakes for superior stopping power compared to drum brakes.