bgeek Backblaze is cheaper if most of the traffic is uploading (like backups).
Backblaze releases a lot of statistics and discusses the inner workings of their system and their support is very good. Haven't seen Wasabi do that.
Personally I found the upload speed to be better on B2 when I tested it. Reviews seem to indicate uptime is better which I would expect from backblaze's system.
Wasabi is cheaper if there will be a lot of download transfer.