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.