Ecolink is a good budget brand. In general, low cost zigbee motion sensors are more responsive than low cost zwave ones. You can find much discussion of this in the forums. It won’t matter for many applications, but it does if you are looking for something to have lights turn on as someone walks into a room. More discussion of this issue specific to ecolink in the following FAQ:
If you haven’t yet, you might take a look at the device class features FAQ, there’s a lot of information there on how one brand might vary from another.
