Here's my current list:
- Apple HomeKit (if you're an Apple user). Otherwise [Samsung SmartThings(). DIY with open source controller are a huge time suck and you'll constantly be doing custom integrations and hitting weird compatibility edge cases.
- Lighting & fan controls: Lutron Caseta. The switches themselves are high quality. They get the LED brightness level correct - the LEDs won't illuminate your entire room at night. Caseta is super easy for 3-way installations- install it as a 1-way and use a bound, wall-mounted remote. Caseta also lets you do simple automations like time-of-day and time-after-last-presence. Beware that there is a 75 device limit per hub and per account, and remotes count towards that. I have to use 2 hubs; I put all my automation controlled devices on one hub and all my voice-controlled stuff on the other.
- Ceiling fans: all of them nowadays come with crappy remotes- before you install it, pull out the remote control module from the fan and wire it as a dumb fan and light. Use A/C fans; DC motor fans need their own special controllers that tie in the motor controller with the remote control receiver unit, so they're hard to automate.
- Deadbolt: Schlage Encode Plus.
- Voice Control: Amazon Alexa. The super easy skills SDK makes this the hands down winner when you want to go outside the box. Also it seems to get little details down more correctly than Apple Siri. For example, if you map your Alexa and your lights to the same room, then you can say "turn on the lights" and it will figure out the room you're in based on which Alexa heard you, and turn on the lights in the room you're in.
- Thermostat: EcoBee. I recommend getting the EcoBee 3 lite rather than the more expensive one with built in Alexa. The EcoBee with voice control has Alexa integration, but IMO it's not that great - I mute the microphone on mine because it always answers the wake word even if another Alexa is better positioned and also answered. I guess it would be OK if your thermostat were far from any other Alexa. Also, it periodically loses connectivity to Amazon and complains. So as a voice assistant, it's not great, but as a thermostat it's awesome, way better than Nest. It also has these little remote temperature sensors that let it average the temperature across a large space, making better comfort decisions.
- Sprinkler/Irrigation controller: Rachio. Super easy to install, monitors your local weather and skips automatically without need of a rain sensor, and adjusts watering for type of soil and slope. It does a really good job.
Some callouts: The most awesome dimmer switches I ever found were Plum Lightpads. Not a good choice now as the app is bound to a proprietary cloud service and the company seems like it's on life support. I supported them on Kickstarter and was very happy with them, but they never did a good job publishing an API and the LED ring was too bright at night- you had to turn it off with the app, you couldn't dim it enough. But man did I love those switches. Nowadays there are a few other touch dimmers out there, but they're all ugly.
I haven't found great smart home speakers yet. Sonos is just "OK", it disconnects from AirPlay when idle and you have to disconnect and reconnect. It does a good job syncing voice to video (at least with Apple devices). The sound quality is good but not fantastic. It's spendy and I expected better for the money. My wife prefers just to carry around a bluetooth speaker that "just works".
I tried First Alert OneLink smoke alarms/CO2 sensors. I really wanted to like them but the setup is clunky, involves a proprietary app (all the proprietary apps suck to one degree or another), the Alexa integration and HomeKit integration seemed half-assed (it's a wired alarm but the QR code is on the side of the device, so you get to do setup standing on a ladder- whee!). Not a fan- I went back to dumb smoke alarms.
Alarm: my home has wired alarm sensors. Nowadays if you call ADT or whoever, they will generally NOT connect the wired sensors- they just use double sided tape to stick a bunch of wireless sensors everywhere. So I bought a Konnected alarm controller and threw out the Honeywell controller board. I had a friend who does alarm wiring for a living, do the hookup and troubleshoot the old sensors. I hooked it up to SmartThings as an integration, and then used the SmartThings home monitoring feature to set up the alarm, and it was super easy and took only seconds. It was astounding. Now that I've gushed, I'm not convinced that the company is on a successful trajectory so that's the only reason I don't come out and recommend it.
I'm thinking about a Span or Leviton smart electrical panel as my next big smart home thing.