i`m using western digital product (WD) usb 3.0 for over a year and i have been living happily ever after with it and no problem so far
but recently some of my friends mentioned that Buffalo is on the fast lane now days, so i`m not sure
but still these are popular products in my country
also when i wanted to buy an external HDD a friend of mine (a gadget maniac ) told some important perks which i`ve written them down, so no matter what kind you wanna buy, be aware of them: (the numbers mentioned are for two years ago so...)
1. External HDDs have two way of connecting. one through firewire (which is the fastest) and another through usb. well now days almost all computers only have usb ports, so firewire is out of the question
2. if you wanna something with fast processing, look out for these three factors:
seek time : is usually around 10 millisecond, but faster ones have it less than 10
buffer size : at least 4 MB, the more the merrier
RMP (Round Per Minute) : mostly 5400 but 7400 is better
3. check google before buying it as a failsafe.
the numbers should be written on the box, so be aware of them