I'm finding spideroak superior to backblaze - it actually backs up my entire system rather than skipping /Library & /opt and allows me to backup external drives without needing to have them constantly plugged in. I think the pay-for-what-you-use model allows them to be a lot more flexible.

Backblaze has been a rock star for me over a year. It used to be very, very slow (My first backup took the better part of a week to get the "Initial" image in place) - but it was okay because their constant background backups only needed around 1 mbit to be effective (and, more importantly to me - invisible. Time Machine had a bad habit of ramping up my CPU).

But, recently, they must have made modifications to their system - because I routinely see backup in excess of 15 mbits/second. Highly recommended.

With an internet connection like that, CrashPlan might be more interesting. The fact that you could back up to a friends computer would be nifty to test.

Backblaze. But it's really cloud backup, not storage/sync like dropbox.