I think that the ribosomes are the most important as they produce proteins for the cell. without them there would be no proteins to feed the cell.
but i think that the ER is more important because it is the organelle which transports all the materials around the cell. without it materials cannot be transported around the cell to be used
however i think that the cell membrane is the most important because it is the organelle that controls what enters and what does not enter the cell. without it bad materials can enter the cell
but i think that the cytoplasm is the most important as it fills up the cell to make every organelle stay in its place. but without it all other organelles will be floating around the cell which could make them hit each other which would cause damage to the cell
at the end we all must know that all organelles are important and that none of them can function alone!!