Based on their controllers:
Quality:
Both give a premium feel but the use of the spring mechanism gives minor issues with trigger buttons and may also lose its tensile nature.
Aesthetics:
Both controllers have a great look, but keys on cosmic byte are a lot better. The LED’s shine much bright and with darkness, the RBG effects look amazing.
Extra Features:
Same features in both controllers,
Cosmic Byte comes with a Free USB dongle, through which you can attach it to your phone's micro USB slot. You can use this free dongle to attach the pen to your driver to the phone.
Preference: Redgear is a bit heavier, and it does not make much difference. Otherwise, Both controllers are alright.