It may be different in different countries.  I think many people would say Openload, Sendspace, and Solidfiles are often fast.

it depends in your internet connection. in my case, i use uptobox, openload and userscloud (just close those pop-up windows or install adblock)

First of all I should re-emphasize the importance of having ad blocking plug-ins as it's sometimes impossible to download from file hosting sites without one installed.
The best one is uBlock Origin available for Firefox and Chrome (needless to say one shouldn't use IE).

And about your question: Download speed depends on one's country, Internet connection speed, time of the day, day of the the week, popularity of the file being downloaded and all the restriction imposed by file hosting and sharing sites, etc.

You should avoid services like SendSpace, UsersCloud, Uploaded, Nitroflare, etc as they don't support resume capability and with your slow connection it's madness to download from them. SolidFiles, UptoBox, OpenLoad and of course Direct (Encrypted Download) are good for you.

And don't forget to use a download manager tool (specially vital for your slow-as-hell Internet connection :)). The best ones are IDM, IDA, EagleGet and great Firefox plugin DownThemAll.