Different ones work for different people. They have some different features. There’s a discussion of the various options and brands in the following thread. The light switch discussion starts around post 40
That said, I like Lutron Caseta switches and ended up choosing those for my own house. Right now there are two methods of integration with smart things: indirectly through IFTTT, or by setting up your own middleman server. But an official integration has been announced recently and may be here in as soon as a month. We won’t know how quick that is relative to Lutron on its own until it actually arrives.
Lutron is an engineering company that specializes in lighting and holds a number of patents. Their target is 300 ms before the switch comes on, which is notably faster than most of the Z wave switches. But again, there’s no telling yet exactly what the SmartThings integration will introduce as far as cloud latency.