I like WeTransfer because it is compatible with all browsers. Also, it has an interface where you can easily drag files. Another advantage of using this tool is that you can see if the people you sent the files to downloaded them. I also like that both files and folders can be attached.

Ease of use, GUI, Speed, log of transfers sent out

It's so easy to send and receive large files internally and externally in a timely manner - additionally, the files don't lose their quality. All you need to use this service is an email address, making the sign up process must faster so you can get right to work.