Thermostat (#1 by a mile) Ring Alarm ($10/mo or $100/Yr) Fire alarm / CO / listener Smart lock (Schlage) Smart hub (HA, Hubitat, ST's) Alexa (cheap voice control) Light switches / bulbs Inside / outside cams Smart garage opener Water leak/Freeze sensor Water shutoff switch Rachio sprinkler control system All of that will put you in a good place. I probably forgot something but after that it's personal preference.