After an extensive review of online backup services, we have concluded that Mozy Pro is the all-around winner for those serious about online backup protection. Criteria for this evaluation included data transfer speed, software features, service capabilities, etc.
While Mozy also offers an unlimited home service plan, we do not suggest it for most due to the capped transfer speed and one problem that was experienced with the home-level service.
Intronis eSureIT is the runner-up in our testing. While their software is capable, and the service offers some very interesting features, such as Intelli Blox and multiple PC backup support, higher pricing, slower transfer speeds, and the fact that revisions count against the disk space quota cause Mozy Pro to come out on top. We have also reported a few suggestions to Intronis regarding usability enhancements that should be made to the software.
IDrive deserves mention. The IDrive software is excellent, and the service works flawlessly for small backups. However, we encountered serious problems when backing up a large collection of files, such as icons or fonts. IDrive provides very attractive pricing. If the issue mentioned above were resolved, we could easily see IDrive moving into the top position.
The only downside we have noticed with Mozy Pro is a delay which often occurs when transitioning between files for upload and download operations. The delay can sometimes be frustrating, but in tests, the overall speed of Mozy Pro still beats the competition.
Update: Please see the comments for an evaluation of the ElephantDrive backup service.