(I’ve moved this to projects so you can get individualized responses based on your own needs and preferences.)
First things first:
When people are considering whole house home automation, they are generally interested in three things:
Reliability
Cost
And Versatility , that is the types of different devices that can be supported and the complexity of the rules you can create.
In high-end systems such as Crestron or control4 you can get reliability and flexibility, but the cost is often as high as 10% of the value of the home, plus an annual fee.
If you make low-cost a priority, that is you are looking to do the whole house for less than $5000, unfortunately you will often have to give up either some reliability or some versatility.
Some systems in the lower cost price range will be very reliable, but they have a much smaller selection of potential devices and while you could set up a rule like “turn on the entry lights when I get home between sunset and sunrise,” you can’t set up more complicated rules like “turn on the Entry lights when I get home between sunset and sunrise unless Michael is already home and is watching a movie.”
Systems which emphasize reliability typically have an MFOP (maintenance free operating period) of at least six months and more commonly 12.
Systems which emphasize Versatility have introduced more complexity and consequently may be more vulnerable to glitches. SmartThings Falls into this group.
SmartThings, at least with the classic app, has amazing versatility because customers can write their own device type handlers, which significantly increases the number of devices that can be used. And they can write their own code (or use code written by other customers) which allows for amazing complexity in rules, but again can introduce vulnerabilities.
For the last 18 months, smartthings has had a platform outage at least once a month every month except, I think January 2017. And in some months more than one. There are also frequent small glitches which can result in a particular device or device class not working when it did previously. Or a particular type of code.
In my own case, since September 2015, my system has had an MFOP of about 10 days.
You can read more about this issue in the following thread ( this is a clickable link)
There are many people who are very happy with smartthings because of the price and the exceptional versatility. they are usually people who like to tinker, who are OK with a system which requires some maintenance every two or three weeks, or which goes out unexpectedly. You occasionally see comments in the forum like “first world problems“ or “after all, how much trouble is it to get up and go over and turn on the switch?“
Then there are people like me. I’m quadriparetic (use a wheelchair with limited use of my hands). After having smartthings for over a year I realized that while I very much appreciated both the price and the versatility, I needed to make reliability a higher priority for my own home system. So I switched all of my critical use cases to something else.
I still use smartthings for convenience stuff like “send me a phone notification if the guestroom window is left open, rain is expected, and the guest is away from the house” because it does that better than anything else in that price range. But I don’t use it for simple things like “turn on the lights in the entry if I get home after sunset.”
Different households will have different requirements in this regard. Some will be willing to pay a much higher price than I can afford. Others will really want the versatility and be willing to put up with the occasional glitches. Choice is good. 
But before we start getting into the details of individual device features, it’s really important to be honest with yourself about your own household requirements with regards to cost, reliability, and versatility.
You may well have already done that, I just wanted to be sure. The marketing for all the systems make them look like they’re essentially interchangeable in these regards, but the fact is, they just aren’t.