Just like @telcodad, I also still have an att.net address from Worldnet. It’s still my primary address. I tended to use the Comcast address for a few things where the att.net address didn’t work. There were sometimes where confirmation emails when signing up would just never show up.
In addition to the Comcast address, I also have outlook and gmail. I may consider making the outlook address my primary now.
I use Thunderbird on the computer, and currently mainly use FairEmail on the phone. I do have Outlook and Yahoo Mail on the phone, too, and of course, Gmail. Outlook and FairEmail cover the 3 non-Google emails. I stopped using Outlook because of the ads, and for Comcast, if I deleted an email outside of Outlook, it would not disappear from Outlook until a new Comcast email came in.