Edge user here. For one, chromium is faster than firefox, any given page will load about 20% faster, another reason is edge workspaces feature, I've grown to like it, which seems to be some sort of chromium feature that everyone bakes in weird ways if at all, and I'm still running ublock origin on edge without any funky bypasses.

Then there's a fact that a bunch of sites/webapps straight up refuse to work on firefox and they ask you to install chrome or something. And lastly chromium the most popular browser flavor and as a web dev it helps to see pages through "the same eyes" as my users/customers.

That's about it, the only reason I use firefox every day is their superior picture-in-picture player, chromium one is waaay inferior.