Hard sleeper. It is the cheapest category among those that allow you to sleep lying in a fairly hard mini bed. In each compartment there are 6 bunk beds, divided into two of three. It is the most requested class for long and night trips, so I recommend you book in advance to get seats. It is also a good way to meet people - especially locals - and start interesting conversations (if you speak Chinese or they speak English, of course).
Soft sleeper. It is basically the same as the Hard Sleeper, but instead of having 6 beds per compartment, here are 4. The price is somewhat more expensive than the previous one and there is a kettle to heat water and some small comfort.
First Class. Ostensibly more expensive than any other. Generally backpackers only die in this when there is no choice. There are 2 bunk beds, 2 small individual TVs, a sofa with small table, wardrobe, kettle and own bathroom (no shower, of course). The truth is that it was a pleasant surprise even if the joke came out 100 euros.
In my opinion the Hard Sleeper is the best option.
The second means of transport we tested was the airplane. We took one from the Capital Airlines Company - formerly Deerair - to make the journey from Xian to Guilin for 390RMB. The train was priced somewhat higher and took 27 hours, as opposed to the hour and three quarters that took us by plane. This time the thing was clear.
You can get flights at decent prices in China if you book in advance or take a last minute offer (this was our case). I acknowledge that I hesitated a little when I didn't know the airline at all and searched on the internet. I did not find it, so my suspicion was increasing only to show that there was no reason when at the airport we saw that everything was happening normally and professionally.
Finally, to go from Yangshuo to Hong Kong we take a bus-bed night. The 8-hour journey cost us 170RMB and was very interesting. On my South American tour of 2008-09 I had traveled in a bed and semi-bus, doing it almost always at night. However, the concept of “bed” that Chinese buses have is much better.
Upon entering the bus we saw that there were no seats that reclined enough, but that they had 3 rows of bunk beds with quite small beds. It was the first time I see something like that. Although the beds are small we were lucky to take the 3 beds behind the driver. We were only 2 but the third bed was accessed through a dwarf hole through which no one wanted to go to sleep next to a Westerner who came out from the side of the bed.
Having known all 3 media, I keep the train for comfort and to enjoy the views of the vast Chinese countryside. The bus was fine but the way of driving in this country puts the creeps and is only comparable to the one I saw in India or Ecuador. It is difficult to sleep with so much braking and whistles, especially because of the continuous perception that the driver's reflexes may have a limit. Seeing these guys I knew why the Chinese were moving so fast in those ping-pong games that they seem to be drawn from Dragon Ball Manga drawings. Now I am sure that all the champions that China has in this sport before were bus drivers (the runners-up I think they were taxi drivers).
Anyway, if you are tighter in time and want to cover a wide territory, as always, the best is the plane. But don't leave without trying the authentic bus-bed experience!