Your recommendations (and warnings) about buses from Hanoi to Sapa
 

We are headed to Sapa in a week and have read so much about all the bus companies that our heads are exploding. What appear to be luxurious and upscale on the website have sometimes been described as uncomfortable and unpleasant, so I'm hoping someone may be able to help us decide which company to use.
We're more interested in the day bus than an overnight train as we'd like to see the views rather than sleep through them. We're also accustomed to the quirks of Asian travel as we lived in Cambodia for four years and travelled extensively throughout the region.
Many thanks!