This question gets asked a lot. I answered it a couple weeks ago here and referred to an answer I wrote over a year ago, with little having changed in the meantime:
As always, "best" means different things to different people. In general, I find Zigbee sensors to respond much faster, which is important to me for indoor lighting. For outdoor lighting as it sounds like you might be using, this usually matters less (you're not exactly walking into a dark room), the extra range Z-Wave might give you could actually be advantageous, and you'll have to wrestle with the historically problematic (absent, really) category of "outdoor motion sensor" that has only recently appeared in the field (Hue and Zooz are the only two I'm aware of that are officially outdoor, but Aeon lets their 6 be used outdoors if reasonably protected--something lots of us have done for a variety of "indoor" sensors for years regardless).
