I can personally recommend
Zen. Smallish outfit based Ooop North, they have a well-deserved reputation for customer service and their staff are regular contributors to Zen's message board on
ADSLGuide, where, unusually, they are often among the first to answer posters' queries.
ADSLGuide itself is also a great place to do some research - you can not only run service-level comparisons with multiple ISP's, but a dip into the message boards, where each ISP has a dedicated forum, will soon reveal what actual customers are experiencing!
Not the cheapest ISP by any means, but you definitely get what you pay for in this market. Zen provide me with rock-solid service that very rarely suffers interruption or deterioration of any kind. Finally, whoever you end up choosing, avoid 'special' offers or deals, as they are rarely very special for long. Good luck!
Jx
