Worst: easily Netweaver. The first year was great, but the second year everything went silly. I registered my domain name through them, but they let it expire; they experienced multiple server problems, but refused ever to admit it - in fact, I had various issues with them, but never did they ever accept that anything went wrong.
Nirmani was different - he had one of managed server pulled out of the datacenter after a very serious hack attack. That server just happende to have my reseller account on it from which all my sites were hosted. He wasn;t sure when the server would be back online. I waited, then pushed - then pushed some more. I was offline a total of 10 days. I ensure that all my important websites are on different servers - even different datacenters - these days.
Best is probably
www.unitedhosting.co.uk - had some great service from them. Customer support has been excellent. Seems to have been much more abrupt of late - more striaght to the point without extraneous words - but I've had a couple of issues that they've still been happy to sort out for me.
I've had more webhosts than that - just a few that stick out - for different reasons.
