Sorry for the slow reply, and I see you've got (and made) one other response. As far as what stack I'm using, on my test lab it's a big mix of course, but my main personal stack right now is UniFi dating back from quite a few years ago. However, I really want to reemphasize my "dumpster fire" aside: I strong
DON'T recommend getting into UniFi right now if you're starting fresh, or at least, if you do be really careful about it. It hasn't been that obvious from the outside if you didn't know what to look for, but from an community and heavy use perspective it's clear Ubiquiti has been having major internal developer issues for a few years now at least. The CEO is apparently pretty toxic, but whatever the reasons are the result has been a major stagnation of the line, both for hardware and software, rapidly increasing technical debt, and a lot of extremely confused moves that seem to amount to easy bikeshedding because real engineers weren't available. I started to get into some of the gory details but am just deleting that paragraph, it's not really relevant here. But to take a specific example, that security gateway you were looking at, which is necessary if you want to use UniFi for L3 features, basics like DNS (which incidentally is also half-assed) etc, is a good 5 years old now. They introduced the "UniFi Security Gateways" and then refreshed them... never. The software for those is stagnant, and core software (like Strongswan for VPN) are often horribly out of date. It chokes doing much of anything interesting, would be obliterated in perf by a current RPi. The switches aren't in quite so dire straights, but for the money they too now have the smell of obsolescence. Ubiquiti has no decent L3 story for 2019/2020, no move to competitive faster networking, and a lot of cruft built up because they like to introduce new things but not just update and replace old ones.
Having said all that, their PtP/PtMP links are still nice. Their APs are solid overall, and do have nice industrial design (though no word on WiFi 6, which for a new install I'd consider fairly important). The interface has degraded significantly over the last few versions, but it's still better and more unified than any other I know of. I mean, I'm still running it myself after all. But if you go that route know what you're getting into and look hard for open box and used stuff that'll be cheap. And I'd honestly suggest not bothering with the cloud key and just running the controller yourself, on an RPi or similar if you want something dedicated but cheap or else spin up a VM or container, or even just run native I guess if you've got a server you run otherwise. The CK is also ancient.
In summary: I adored UniFi, and the potential was(is?) fantastic, and their old vision was fantastic, and at one point they were a really solid venture all around. And I know of nothing else with the same vision either. Yet even so I'm expecting to have to dump it overall in the next few years, which sucks. But long bitter experience has taught me that glorious turnarounds are much more the exception than the rule :(.