Eclipse residential
I never really understood why they abandoned new residential users (about 2 years ago) via their Eclipse residential brand. I've been with Eclipse for about 13 years (starting on 500kbps ADSL, now on FTTC) - they're not the cheapest but I've always found them pretty reliable and with good service. They do occasionally feck things up but they always sort things out and you speak to someone in Exeter that IME isn't reading from a script.
For now they're supporting existing customers but if they give up on that too I'll be considering A&A or Zen (who seem to be closest in service and customer satisfaction).
I suppose they either didn't have much confidence in their product, or in their ability to pull customers away from the mass market where TalkTalk style "6 months free then £5.99/month - min 3 customer data breaches per year and scripted Mumbai call centre" offers are king.