Answer:
Aquarium decorations should serve two purposes. It should be aesthetically pleasing to you and functional for the fish. Certain types of fish need certain types of cover and hides. If breeding is a concern it can get even more in depth as some will only lay on plants some on wood, some on slate, some in caves, etc.. Your best bet is to study the fish you have or want and try and replicate its natural habitat as best you can.