In my case, Synology has worked fine. Reliability is a big deal for non-backup RAID (not the same as "backup," but does the trick, 90% of the time).

It's entirely possible that their newer units are crappier than the old workhorses I have.

I don't use any of the fancier features that might require a beefier CPU. One of the units runs a surveillance station, and your choices for generic surveillance DVRs is fairly limited. Synology isn't perfect, but it works quite well, and isn't expensive. I have half a dozen types of cameras (I used to write ONVIF stuff). The Surveillance Station runs them all.

Synology's fine - even ideal - for that use case. If you want to run Docker containers, run apps for video conversion like Plex, etc, then you'd likely want to consider something with a beefier CPU. For an appliance NAS, Synology's really pretty great.