I like Smartthings. Is it the best? No. Is it the most functional? No. But it supports a lot of devices and it’s really easy to use. And coupled with Alexa, there’s very little you can’t do. For more complicated things where it might seem impressive, the key is often virtual switches and sensors.
Steer clear of smart bulbs if you can and rather use smart switches. For light plugged into a non-switched outlet, use a smart plug in module.
I have a smartthings hub with Inovelli Blue 2-in-1 dimmer / switches and Jasco plug in dimmer modules. I have my bedroom floor lamp plugged into a switch, while my bedside lamps are plugged into dimmer plug in modules. When I press the on switch once, I turns on just the floor lamp. Press the on switch twice, it turns on all the lights in the room, all to my preferred evening dim level. Press the same on switch 4 times opens the zigbee window blinds in that room. The options are pretty much limitless, and really only limited to your imagination. Oh, and I have Echo Dot devices in each room to facilitate voice commands.
I have my meross account linked to smartthings. That’s literally all you have to do. I have a wireless zigbee up/down switch that let’s need open and close the garage door. Or link your meross account to Alexa and control it with your voice from anywhere. Or both! Loads of combinations.
I use a combination of Smartthings and Alexa. Alexa automation is very simplistic and limiting, but combining it with smartthings, you can do a lot. There are certainly limitations, but a lot can be overcome by familiarizing yourself with virtual edge devices in smartthings virtual switches and virtual sensors are a great way to effectively allow two way communication between Alexa and smartthings.
I kept mine simple and used a smartthings hub to handle my zigbee needs and make up for Alexa’s shortcomings. Those two really do complement each other will, especially when you discover the usefulness of virtually switches and sensors (particularly a virtual Alexa by, which operates as a switch but behaves like a sensor, so you can trigger Alexa to do things from outside of Alexa)