We have both wink 2 and SmartThings 2. For the last 18 months I would say that smartthings offers the ability to do much more complex rules, but Wink has consistently been more reliable. We have had an MFOP (maintenance free operating period) of over six months for wink: with SmartThings, we are lucky to go 12 days.
Smartthings has had at least one outage every month for the last 18 months except, I think, January 2017. Sometimes these are pretty minor, sometimes they are very annoying. 
SmartThings Does a lot of updates and improvements, which is good, but that also leads to what is hands-down the most frustrating aspect of the platform: things which you had set up and running perfectly for a couple of months which then just stop working one day when you haven’t made any changes. This happens frequently. And most of these do not get posted to the official status page, for whatever reason.
Here’s a current one, which is typical:
You can see a list of the community bug reports in the community – created wiki:
http://thingsthataresmart.wiki/index.php?title=Bug:_First_Reports
People who are tinkerers, very budget conscious, happy to spend an hour or two on maintenance and troubleshooting every week, and really enjoy seeing how far they can push the logic for a home automation system generally really like the SmartThings platform.
People who don’t fit that description may find that other systems suit them better. Different things work for different people. 