I've been with NewNet about 6 years. Availabilty and speed is good with very few outages. Technical support is UK based and first class. Downside is price, you can get cheaper elsewhere but you do get what you pay for. 12gb cap is starting to become an issue.
I've been with them for about 4 years. Their service has been reliable and their support first class. They do not 'throttle' traffic. When I've messed things up and sort their help they know what they are talking about and patiently put you back on track. A bit more expensive than the main players but well worth every penny.