I've been an A&A customer for 12 years across 3 house moves and a recent upgrade to their FTTP service. They're not the cheapest but I firmly believe that you get what you pay for, and in this case that's an incredibly reliable service with exceptional support available over pretty much every communication medium except carrier pigeon (although I wouldn't be surprised if they're working on adoption of RFC1149).
Of the few incidences of downtime we've experienced over the years, I can't think of one that wasn't either caused by a fault in my own network equipment, a careless OpenReach engineer working on a nearby cabinet, or the one time that lightening hit the telephone pole outside our house and melted the phone socket. In every instance, their support staff were responsive, efficient, and a pleasure to deal with.
Time With Provider: 12 Years
Package Name: Home::1 FTTP