I've been really happy with AA for the past few years and just went through a house move. There were some problems with OpenReach availability in my area, once I'd made the order they called me up and talked me through some options and gave me a great recommendation for a restaurant in my city as well (added value).
Over all the service has always been great, during COVID I hit my usage cap and got an email saying they'd given me some extra headroom due to COVID. It was super helpful and showed a lot of awareness of what customers were going through.
Speeds have never been a problem and now I can get Fibre-to-the-Property (FTTP) they're even better. Stability has also never been a problem, I've been with them for about 2 years now and only had one outage due to a 3rd party. I called up when I'd done some basic troubleshooting myself and they explained the situation and made sure I got text message updates as things changed.
I'd caution to say that they're probably not a great pick if you're not somewhat IT-savvy. The web interfaces to manage your account aren't very friendly and they're not afraid to talk technical. I probably wouldn't recommend them to relatives unless I was managing the service for them.
They even include static IP's which is brilliant!
Time With Provider: 2 Years
Package Name: Home::1 (FTTP + 5TB usage cap)