Right now I am still using Mozy Pro but I have looked at Jungle Disk and like it so I think I will change.
I use Jungle disk and it works well. Jungle disk gives you a choice between Amazon and Rackspace. Note that Rackspace doesn't charge transfer fees, while Amazon does.
I am also looking at Crashplan
www.crashplan.comas another backup option. After mozy yanked their unlimited plan, a lot of people seem to be switching to crashplan. What intrigues me about crashplan is that it allows backup to a local external drive, to the cloud, AND to a remote drive at a friends house. All backups are encrypted.