I'm using backblaze for several years now. The client it is not that wonderful in terms of configuration but it does its job. You can configure how many threads you want to be sending at the same time, by default it is just 1 thread, and that should be enough for daily basis, for first backup I will recommend to increase it, so it can take the full advantage of your bandwidth.
I have never had to recover it yet, luckily, but I do regular checks downloading random data from it and checking if it works. As they say, any backup it is in an indeterminate state until you try to recover from it.
They have 15 days or one month trial, so you can check the client yourself to see if it fits your needs.