First, considering the economic situation and the higher the elevator building, the more expensive it is, the 10~ 13 floor is a good cost performance, because the old residential buildings are all 8~9 floors, so the elevator building generally needs to be above 10 floor to have a broad view;
Second, if the focus is on comfort, 3 1 floor is the best choice, and there is nothing to say about vision and ventilation, and there is a sense of dignity.
Third, if we consider the psychological characteristics of customs, the eighth floor is not very good. Westerners have taboos about the number 13, and the 18 floor has the saying of hell 18 floor, but as a modern person, this taboo is really redundant. Some 18 floors are actually more affordable, so they are unhappy.
Fourth, regarding the ash layer, there is no need to worry about the street-facing houses above 10, and the dust has basically settled;
Five, about personal feng shui, look at the master's feng shui eight characters, this is a special study;
Generally speaking, floors 15~20 are better choices (as for the landscape, it should be adapted to local conditions).
Also, the information you gave is relatively small, and I don't know what your main considerations and concerns are, so I want to make a brief analysis.