For home automation, look at:
https://www.smarthome.com/
If you see something you like, do a web search to see if you can find it at a better price. I have a Insteon Hub and several devices. Easy to set up, and easy to use. You can turn on/off lights, view cameras, etc. when you are away from home with your iPhone.

I have Cox cable, and I'm pleased with their service. Haven't used ATT for home, so I can't compare the two.

There are several different mesh systems out there, so I recommend checking out CNET reviews. Believe they do non-biased reviews.

As for a doorbell camera, you might be stuck with a Ring. Service for a period of time is included, then they charge you a monthly fee to see any recorded video. You can still see it live without the service, but that's all you are allowed to do.

Have fun shopping!