Although I used several cloud services like Dropbox, Google drive, and Box etc., I am interested in "copy". The reason is a capacity.
Just after sign up, you can get 15 GB. Further you and invited person get 5 GB for each if you invite someone.
If you are interested in please use following link;
https://copy.com?r=TjHOZZ
Some guy increase his capacity about 1TB. Amazing.