For me, it would be security, mostly. Most of the cheaper smart switches have questionable security, to say the least. Often, security updates are not provided in a timely fashion (or not at all) and configuration options to reduce the attack surface are sometimes missing, like the possibility to isolate the switch management GUI or console by putting it on a distinct VLAN or switch port, separate from all other VLANs like your DMZ, for instance.
At the time I bought my Cisco SG250-08, there were no 8-port switches supported by OpenWrt, unfortunately. So my main reasons for buying the Cisco as opposed to cheaper options were:
- Cisco provides somewhat regular updates, at least for a few years.
- The management interface can be put on a distinct, isolated VLAN.
- The web interface is optional. I can manage the switch over SSH wit public key authentication and can disable the web interface (and other network services) which reduces the attack surface greatly.
- I'm not forced to use any cloud service and the management interface or switch itself doesn't require any internet access.
Now, if I were to buy a new switch nowadays, I would definitely go for an OpenWrt-supported device. This would provide even better security support over a prolonged period of time. And as mentioned before, I could use the same UCI syntax to manage the switch that I can use, e.g., on my access point running OpenWrt.