To get back on topic.
Personally I'd recommend Zen.
Quite funny, in view of your experience.
If you'd read the threads you'd see there was an issue with the PM system and one of my replies did not get back to the member of staff that was trying to carry out BT checks for me.
I made a bit of a harsh comment which I retract indicating that I thought the person may have got bored when I should have perhaps asked whether the PM had been received.
When I rang technical support and enquired about the socket replacement a fault was raised to get it replaced no questions asked.
As I've explained before when you've added little more than additional disk space requirements with your replies I'm very glad that BE does what you need but all I got when I tried O2 (which used the same infrastructure when I tried them which I verified from a trace route) after being a happy O2 mobile customer which I still am was a flappy line, no attempt to carry out any diagnostics before sending a BT engineer out and when I tried to claim on their money back guarantee after returning their equipment some call centre guy demanding I send in bank statements to someone he would only call 'Mark' after he kept insisting that they had sent the money but my bank confirmed nothing had been received.
So personally I wouldn't touch O2 ADSL or BE with a barge pole now but then again that is my personal experience. but I am always wary of ISPs.
I also had a bad experience at plusnet which was so bad in fact I bought myself out of the contract as they did not offer monthly terms then.
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen Lite 8000
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.