Any drive with a backup is better than no backup at all. You will find lots of different people with personal preferences based on the storage devices that have previously worked well for them. I suggest researching which name brand storage devices are offered at the best price. The prices fluctuate, and you may find that doing your research will allow you to buy an even larger storage device at a price lower than what you can find a 2TB device for. With that in mind, I am sure you will receive responses from others that have personal recommendations. I personally own 1TB, TB, 3TB, 4TB, and several 6TB hard drives from a variety of manufacturers, and they all have performed well using Time Machine and Carbon Copy Cloner.