A&A are fantastic, yes they are a bit more expensive but they really do outshine every ISP in the UK with their no-bullshit attitude, and I love the way they take BT to task when things aren't 100% working properly.
I used A&A before I moved to Ireland and really miss them. I'm stuck with Eircom (there is virtually no land-based provider choice in Ireland if you live outside of Dublin) who are a financial basket case and suffering from virtually no infrastructure investment outside of Dublin.
Internet access in Ireland is like the UK was back in 2002/3 and the Irish government wastes millions of euros on half baked 3G/Wireless schemes that don't work instead of fixing the terrestrial system properly.
You can get a good idea of the company's general philosophy from their owner's blog: http://revk.www.me.uk/
Unfortunately they are quite expensive compared to the bigger ISPs but in their case you really do get what you pay for.