Which is the best drive to backup yur blueray movies?

i have an 2tb data collection of blueray movies and videos, it is an very unique and precious collection, i spent my last 2 years in downloading it, now i want an 2tb portable hdd to give it an backup.
My first choice was to pick an 2tb portable segatte hdd but i came to know that 2tb hdd of segaate require an external power supply i.e they are external drives, i just wanna buy portable drive.
My few friends suggested me about buying an wd 2tb portable hdd.
I do not have much confidence on western digital hdd, please help me guys as i dont wanna lose my precious collection.
Help me with choosing an hdd