Honestly, the best bus ride I've had so far has been Mong Cai to Hanoi from 11PM - 6AM. Staff were polite and helpful, and unlike other rides, it was easy to sleep, because the driver wasn't constantly honking. I woke up at 4:30 AM in time for a bathroom break, and the facilities were clean. It's definitely a budget bed, but as a short queen at 159 cm, I was able to fit with my shoes and backpack. USB port works, and with the Viettel 8 gb/day plan, I had plenty to keep me entertained. Water is provided, and the only real negative was a loud auntie on her phone. (not much to do about your neighbours!)