I've had excellent experience with Plusnet. They're advertising themselves at the moment with their cheaper plans, but I'm paying more for an 'unthrottled' service. We've got BT Infinity in one house, but there is a massive slowdown at peak times; the service is much more consistent with Plusnet. I'm guessing that BT have a more overt Transparent Proxy server policy as well, as I get a lot more random page errors.
Plusnet offer static IP addresses for no extra as well. And like someone told me once, 'if you don't know what a static IP address is, you don't need one".