I only know of two that fit that particular description:
Homeseer (they released a version in 2020 which adds zigbee support). They’ve been around a long time, and it’s a powerful and highly customizable system, but it does require significant technical expertise and it is more expensive than smartthings. Also, no consumer friendly app.
Hubitat. Created by smartthings power users a few years ago, many aspects are highly similar to smartthings as of 2019, with the exception that everything runs locally except for integrations to third-party cloud-based systems like voice assistants. Again, this requires significant technical expertise and the most obvious area where things are very different is that there’s no user-friendly app like smartthings has. You can use sharptools with it, though, and that’s a good solution for many people, particularly if you were already using SharpTools with smartthings.
So both of those are highly customizable, have active developer communities, happened to both run primarily locally, and now both support both zwave and zigbee. But both require a lot of technical expertise and are not off-the-shelf consumer friendly.
And there are also some “roll your own“ options like home assistant which are popular with some groups, particularly if you have strong technical skills. But for those you don’t buy a hub, you have to select your own hardware and put everything together From a software perspective. It’s just a whole different kind of project.
CONSUMER FRIENDLY OPTIONS WITH NICE APPS
If you’re looking for something with a nice app, and that doesn’t require the same kind of technical expertise, then either apple’s HomeKit or abode are possible candidates. But neither matches the customizability of the previous group.
- Apple is particularly attractive if you already have an iPhone, since there are no subscription requirements, everything runs locally except the voice assistant (and they are adding more local options for that), and they are all in on matter support for the future. And the app is very nice.
On the other hand, zigbee support is limited for right now to what you can add through bridges like an Aqara Base station, although that may change in the future because of Matter.
And there’s no zwave support in HomeKit itself unless you get into technical options like homebridge.
So going to Apple HomeKit might mean replacing a lot of existing devices. But you do get a nice easy to use highly reliable plug and play system with a consumer friendly app.
- Abode is particularly good for security systems, but does have a required monthly fee and they haven’t said anything about matter one way or the other yet. They support both Z wave and zigbee, but with a limited selection of devices. Nice app, though.
HOW MUCH WILL MATTER MATTER?
So every system has pluses and minuses. I would note, however, that it really is possible that Matter Will change a lot of things in the home automation space by December 2022. Including for smartthings, who have said they are going to support matter, although they have said a lot of things in the past that didn’t quite happen the way people expected them to. (Bluetooth and local processing are just two examples. Oh, and lighting groups.)
More discussion on matter in the following thread (the topic title is a clickable link)
MY OWN CHOICES
If I were looking at a new system right now, my top candidates would probably be hubitat and HomeKit, Hubitat Because it’s the most similar to smartthings and Homekit because it’s very consumer friendly right now and the commitment to matter is pretty exciting.
But I’m not looking for a deep dive technical system or to do my own programming, so again, different things work for different people. (If I got Hubitat, I would have to pay someone else to do a lot of work on it, which of course adds to the cost.)
Check the other threads in the “other hubs“ section of the forum and you should find lots of discussion.