I've been playing with automation since X10 was new. (which gives away my age a bit). After many systems I had an Indigo installation with all Insteon. I had some issues with failed devices and decided to move to Z-wave. As time progressed, I wanted more control I wanted door locks, and voice control. At the time, Indigo couldn't do door locks with Z-Wave. Then came Homekit and Alexa control and again, initially, Indigo couldn't offer voice control.
I moved off Indigo to Vera. Then Smartthings. Then, just play wifi devices and Homekit.
And I'm moving back to Indigo. Wifi devices are horrible. I have a strong mesh network and I still have issues with wifi devices responding reliably. One day, I open my Home app and find no devices. The iCould sync got hosed. I tried everything and ended up logging out and back into iCloud. I had to delete and reinstall every wifi device. I use with Alexa too so I had to repeat for that. A royal pain. Not to mention, all my automations were lost.
Indigo is not the cheapest solution. $250 for software, plus interfaces plus a yearly fee. It's worth it. It now supports Z-Wave locks. And through plugins, I can even have my Siri and Alexa voice control. I still have about 1/2 dozen wifi only devices with no plugins for Indigo (iDevices Inc stuff), but everything else has plug-ins. In face, I even connected my Lutron hub through Indigo and used Indigo HomeBridge instead of putting the Lutron stuff directly onto Homekit. If iCloud sync every gets hosed again, I can all all the devices back in one step thanks to home bridge.
This isn't even mentioning the superior control you can have with Indigo. But for me, it was about reliability. Granted, Insteon and zwave have issues, but with a few repeaters you can end up with a very reliable system. I also love that adding Insteon gives devices you just can't find. Ironic that I moved to Z-Wave initially due to the greater selection of devices, but I couldn't find anything like the in-line fan controls or keypads with custom laser etched labels.
As far as leaving a mac on all the time, I ended up picked up an older Mac Mini for about $100 on eBay or macofalltrades (i don't remember which). I wanted something that could run at least 10.12. It's actually an advantage not to update all the time so you can save some money if you get a model that doesn't run the absolute lates OS. I wiped the machine, set it up with Carbon Copy Cloner doing a hard drive clone weekly so if it every had a drive failure, I just pop in a new one and I'm back up.Mini's are pretty low power and with remote screen control, you don't need a monitor. It's working great.
Just wanted to share a little of my experience for new users. No home automation solution will be perfect but take it from someone that has tried just about everything, Indigo is a great solution and if you have issues, Matt and Jay are fantastic.