Really good question
From my experiences I believe that everybody at some level agree to say that service is important. However I've encountered many occasions on which clients and even hosts mix things up altogether.
For example some clients believe that the host should provide basic assistance in using technologies like PHP, PERL, MySQL, etc... At some point it can be more like teaching than support or service 😉.
On the other end, some hosts expect all clients to have the required knowledge to operate their account on their own.
And of course there is the billing /registering service, which is quite different.
My advice would be (on the service issue) for a client to look for what he needs based on his knowledge. The most he is at ease with technology, the most I would recommend looking for hosts who provide written guides and documents about their services that can help him solve problems on his own. If he wants more direct interaction, just write an email to them before registering and ask some information about them or their services or some technical stuff. If they take the time to answer and he finds the reply fast, proper and useful, chances are they will act just the same once he has registered. ( it is however never a guarantee )