Laura's DH here:
OK, I have been researching this for sometime, and as such, I have got more informed (i.e More Confused then Ever).
First, as to the goal/case study. I have a house with Low Voltage 50's Switches, I have to replace them to sell the house. I also need to implement Security and Smoke/CO Detectors, and have a old Honeywell round thermostat (Pre-60's). I decided since it is high end sale, it would be best to add smart. SO I found:
1. Platforms - I want it to work on Apple/Android and Windows. I know that there is Homekit, IRIS, Smart Things and Wink 2 as your main Bridges, and Applications thereto to run these. The control applications to monitor and setup vary greatly in Feature and Function, so I want to discuss each here.
Smoke and CO Alarms - This is a basic feature in a house. It is rarely used, but when needed needs to work well. I believe First Alert and Nest are my best choices. NEST is really cool, and works with Smart Things I believe and WINK 2 hub. I am leaning towards Wink 2 hub or IRIS. IRIS HAS A BIG PRICE ADVANTAGE BECAUSE OF THE LOWES OWNERSHIP. I spoke with someone at Lowes who also uses the IRIS equipment but he prefers his WINK hub and not the IRIS Platform. From my understanding there is a cost monthly to move to IRIS for most features to work, i.e advanced functionality.
Thermostats - I like the Ecobee, but frankly, the new buyer most likely could care less and a Honeywell from Lowes with the IRIS or WINK 2 may be great. What would be the argument for the more expensive ECOBEE. What makes it better. I could not see it, but they do look cool.
Electrical - I reviewed Phillips HUE, really cool stuff. But 49.99 to 60 for a Light bulb, a bit on the pricey side for a sub $10 LED Light Bulb. Really cool, will look in my house, but I think Smart Dimmers from GE or Lutron could fit the bill. GE is lower cost if you go with IRIS, but again is there a cost to run the app.
Camera's and Security - Would love recommendations on this, it looks like again IRIS has a pretty good solution. NEST are really cool, and I am unaware who the leader is. Would love feedback.
Doorbell Camera - Ring is pretty cool add on.
Door and Garage - Shlage has a deadbolt that matches my current Slage Door Setup, and my LIftmaster Door has a WiFI Option. So I am good on these items.
This is tough to figure out, truly in it's infancy, but very affordable options on the market, and some very not so affordable but cool options also.
As to standards, Zigbee and Z Wave and IFTTT are all fine and dandy, but I am looking more at feature function. I believe Zigbee is a good standard, however, IRIS for example does not work with all Zigbee devices, and Wink2 same, so I guess this is cost of early adoption.