Are these running a free-software stack? Couldn't find info about it since fortinet website blocks Tor traffic.
OTOH I know a lot of people who are pretty happy with them, but that might relate to the fact that I recently started at a company selling them (among other brands). What impressed me most was the well executed "single pane of glass" integration of the first deployment I saw; all switches could be easily managed from the FortiGate web interface. Compared to that the Unifi Manager feels like a chaotic hack job from the 90s.
(To be fair, at home I still use Unifi APs and the switches are based on bang-for-buck: The 8P GBe 2P SFP+ Mikrotik in the study and the 24P GBe PoE 4P SFP+ Aruba as a "core" in the basement [that is, once it arrives, for now an ancient Netgear switch has core switching duty], Firewall is a loaned FortiGate, which I will probably replace with an OPNSense when I have to return it -- I'd go all FortiNet if the basement switch alone wouldn't cost about as much as my PC, though).
Haven't run into any issues with Fortigates, yet. Time will tell.
Thats for Firewall/nat/router style devices, for wireless we've got a large number of unify flying saucers. I've use mikrotik wireless in the past, but it's not on the same level at all.