The best for me is MyAirBridgehttps://www.myairbridge.com
Use enough to work in sending large files to clients. Have several very good advantages:
1. Send files up to 20GB free.
2. Creates a link from the start of the upload giving soon to send without having to wait for shipping confirmation email .
3. If the net go down he goes right after reset.
4. You can just put the data right after uploading start