I originally suggested that Pipex were a good bet. At the time I went with them the offer was on their 'Extreme Solo', which is still good today I understand.
However, that was over 6 months ago. Never one single problem and it always connects very quickly at 576 Kbps(I just checked)
All for £23.44 per month - including VAT.
The choice, as they say, is yours.