I use both. A single rotor cover more area that a pop up and can be kept on the edges whereas pop ups for a large area would have to be placed out in the lawn as well. A pop up is great for small areas where a rotor would be too much, but if your water isn't really clean, the screen in the pop up will clog and have to be cleaned frequently. The reason you can't mix rotors and pop ups is they put out different volumes of water in a given period of time. Actually, I have mixed on zone and it works OK, you just can't exceed total volume per minute.