Custom cooling solution, I/O type & numbers, colour scheme, size, value added feature like LED lighting etc, OC ability (not much difference anyway cos all use same chip)

Just buy the cheapest. No significant difference except minor clock speed.

I have used many brands...ASUS, Gigabyte, Saphirre, PowerColor, MSI.

All no problems. Just don''t buy unknown brand you never heard b4.

If u check the garage sales for used very very old GPU, those >5yrs old type

usually u see more brands like Asus, Gigabyte, Galaxy, zotac still selling and working

u wont see MSI, leadtek, sapphire, infact MSI is the least common.

All that can tells u how reliable a brand is.

I have good experience with Gigabyte & Galaxy. Their GPU can last quite long. Gigabyte particular last easily 5yrs without problems.

Another tip is if u are getting a GPU with long PCB(printed circuit board), it is highly recommend u get those with a backplate on, so to prevent card wrapping. Card wrapping is bad in long time will kill GPU.