Whatever you do, don't buy a QNAP. I have no idea whether Synology is similar, but I am having a hell of a time recovering data off my dead QNAP TS-453 Pro because they make it almost impossible to repair without specialized tooling and the on-disk format is using a custom version of LVM that's incompatible with standard Linux. The reason why it died was because of a manufacturing defect in the onboard Intel J1900 chip that QNAP knew about, didn't do a recall for, and refused to provide proper support for. The disks themselves are fine, I am just forced to buy another QNAP just to access the data. After this experience, I swore off using turnkey NAS boxes. If your data is stored in a proprietary box that's unrepairable and using a disk format that's non-standard, that data is not safe.

Now I have a self-built DIY NAS that I've setup with Arch Linux and OpenZFS and I am pretty happy with the results. Sure, going SSD over HDD is an expensive choice, but given that I had to replace each hard drive in my QNAP 2-3 times each over the span of 7 years, I think the cost balances out and the extra performance is sooo worth it (80MB/s vs 700-1000MB/s).