I realize the question may sound rhetorical, but help me choose the best option!
I can not give you a definitive answer, because the choice of plastering material depends on the material and evenness of the walls, the climate of the room, the availability and price of materials, the conditions in which the work is performed, etc..
I believe that cement-sand plaster has more advantages than disadvantages.
1. Low cost of the material itself.
2. High durability of the finished surface.
Gypsum plaster can be easily scratched and dented by light impact with hard objects.
3.It is suitable for damp areas, for facades, for buildings without heating.
Disadvantages of cement-sand plaster:
1. Difficult to handle.
2. Final puttying for wallpaper or painting is required.
3. When plastering the metal and the wood must be covered with a metal grid. If the plaster layer is more than 30 mm thick, a grid is also needed.