Every system has its own pluses and minuses, so it just depends on what your own particular needs are.
As documented in a couple of different places in the forum, I moved most of my critical home automation over to homekit about a year ago because as a person who is quadriparetic I need reliability. However, it has a lot fewer features than SmartThings does.
I keep hoping that SmartThings’ reliability and stability will improve, as that’s really my only concern about the system, but they’re just not there yet.
So different things work for different people. SmartThings is definitely not a “set and forget” System at the present time, but it’s undoubtedly one of the most versatile systems available, so if you like adding the latest and greatest devices on a regular basis, it’s hard to beat in that regard. And the community is outstanding. But it does require a lot of ongoing maintenance right now.
One of the uses that I’ve kept SmartThings for is when I want to track something from more than just the moment of the trigger event. For example, as of iOS 10.3, HomeKit can now tell me when the linen closet is open. But SmartThings can tell me if the linen closet has been left open for three minutes. Or if the guestroom window is open and rain is expected.
So for simple, reliable, and very low maintenance, HomeKit scores high. But SmartThings is a much more powerful system that can do much more complex logic. Just not necessarily right at the moment when you want it to.
