If you're just using it purely for storage to serve up to clients on your network, I'd go with truenas. If you need the performance of raid, I'd also go with truenas.
If you're trying to build an all-in-one media server, unraid is a great choice. To be honest, though, I don't like it for much else, and you have to pay for it.
Synologies are a good option if you need a pretty simple solution, but like you said, you're definitely paying a premium for that simplicity.
It kind of depends on your use case.
If you're just using it purely for storage to serve up to clients on your network, I'd go with truenas. If you need the performance of raid, I'd also go with truenas.
If you're trying to build an all-in-one media server, unraid is a great choice. To be honest, though, I don't like it for much else, and you have to pay for it.
Synologies are a good option if you need a pretty simple solution, but like you said, you're definitely paying a premium for that simplicity.