Most hosting companies can be measured by the degree to which you do not have to contact their support department. However when the chips are down (along with your client's website) that's when you know how good your hosting provider really is. We had a recent incident (thanks to the current prevalence of WordPress D.O.S. attacks) and 4GoodHost were brilliant.
They were incredibly helpful, available on the phone and proactively called us with updates. They resolved the issue, making recommendations during the process. These guys rock!