Re: Quality of Service is probably more important to me
After years of latency, lag and buffering problems with VirginMedia I switched to a different ISP and my connection has been flawless ever since. Changing ISP's could potentially bring back those kind of issues so that is my reasoning for not switching.
The peace of mind and quality connection is worth the couple of extra quid.
Three have not kicked me off the totally unlimited One Plan yet so I can tether 4G as much as I want, so any downtime between switching ISP's or say moving house is not an issue.