Kim Dotcom's MegaUpload revenge site, Mega, has been live for only a few days and is already very, very popular. It proved so popular that it wasn't able to cope with the initial traffic.
Those problem have mostly been solved now and Mega keeps on adding new users, to the delight of Dotcom who's bragging about the site's Alexa rank.
Granted, Alexa ranks are anything but accurate, but they're the best thing we've got. Dotcom boasts that at this point, Mega.co.nz which is only days old, is doing better than both Dropbox and Rapidshare. In fact, Mega is now the biggest New Zealand site in the world.
That said, Rapidshare has been losing traffic for a while now as it tries to transition from a cyberlocker to something more akin to Dropbox.
As for Dropbox, most people use the desktop and mobile apps and rarely visit the site so that's hardly an indication of usage. Mega, on the other hand, is only accessible via the site.