It depends on what you want to do. Being that you have a gaming channel I'd go with 1, which is the cardiod mode. It will capture sounds best from the front of the mic and other sounds will be harder to catch. This is good for if you're singing or speaking and you don't want other sounds (controller, clicking, etc.) to be caught in the recording.
This is from the Blue specs:
1.Cardioid mode: Well-suited to podcasts, sung vocals, and other voice work, cardioid mode records sound sources that are directly in front of the microphone. It delivers a rich, full-bodied sound. 2. Cardioid mode with -10 dB PAD: The same as cardioid mode, except with a -10 dB attenuation that helps you capture louder sounds with higher fidelity.
3. Omnidirectional mode