Not the cheapest ISP, but if reliability, performance and service matter to you, you definitely get what you pay for.

Great engineering staff you can actually talk to if you have a problem, not hidden behind layers of call centre drones. When you really depend on your network connection, this is invaluable. Having said that, I've only had two problems in ten years that I called them about, and one of those was BT's fault. AA got it fixed rapidly.

Network performs really well - generally doesn't slow down at peak periods, just when you need it.

I love the control pages. If you know what you're doing, these are just great! I use A&A's SIP-based VoIP service, and have traffic shaping enabled. Gives me low-latency service all the time, no matter what download is happening, for a slight reduction in throughput. No-one else seems to understand that low latency is more crucial than that last 5% of bandwidth. Being able to see traffic graphs is great for diagnosing that something on my LAN is misbehaving.

I just upgraded from ADSL to FTTC. BT Wholesale screwed up the upgrade, but A&A were great at holding them to account on my behalf and getting things sorted out. Currently getting a solid app-level throughput of 36Mb/s down and 9Mb/s up.

And I have static IPv4 addresses and IPv6.

So, not the cheapest, but definitely good value for the service you get.