Totally disagree. AA provides more features and these are very important to me; line IP bonding, fixed global IPv4 address blocks, IPv6, constant quality monitoring graphs, alerts when your lines go down and many many more - can’t think of them all. The IPv6 and fixed IPv4 were requirements for me, that’s why I didn’t stay with Zen, although Zen has changed since then; it was a long time ago. AA policy also guarantees a contention free network. So it’s not all about customer service. Many people are not interested in these things and just, understandably, regard internet access services as a commodity. Hence the race to the bottom on price.
At the same time, your line is what it is and won’t get better by a change of ISP unless it needs mending. The core network does also matter though.