Ideally I'll always have both. I just got my first ztr after years of using only a walk behind. the ztr is great for wide open lawns but on smaller lawns the WB is more convenient and precise. Plus I really don't like sitting all day long. They both have pros and cons . Depends on your lawns and if a ztr will really increase efficiency or not. I've found a few of my big lawns have steep hills or tight spots I can't get close to with the rider... so I end up w more trimming unless I use the WB on those parts.