By coincidence I just spent several hours today comparing exactly these two services (Wasabi vs B2) and even though I am familiar with Backblaze and have used it before, I went with Wasabi. It's basically the same price, has more regions, a very simple interface, and rather than having to manage both hot and cold storage Wasabi is cheap enough to just throw everything into hot.
The only downside I found is that they limit free egress to 100% of your storage (so if you store 1tb, you get 1tb egress). In practice I don't think this will be an issue for my use case.
So I'm an example of a person who this morning had almost never heard of Wasabi, knows Backlaze well, and after an hour or two of research I have completely switched over.
Isn't B2 cheaper than Wasabi? B2 is $6/TB while Wasabi is $6.99/TB. Why would you have to manage hot and cold storage with B2?
Wasabi also treats every object as having a minimum 90-day storage period. So if you upload something and delete it, it's still considered "stored" for billing purposes for that 90-day minimum.
B2 also gives you 3x storage as free transfer compared to 1x for Wasabi.
I'm not saying you shouldn't go with Wasabi, but the reasoning you've articulated doesn't seem to track.
Additionally, Wasabi bills you for a minimum of 1TB of active storage, which is $6.99/month. For my modest backup needs it is way cheaper to use any service that bills per GB.
Wasabi also charges objects at a minimum 4KB of storage, which isn’t great if you have millions of files at 1-2KB.