I need to replace my aging Qnap 219P with 3TB. Preferably, I want to buy a QNAP as I should be able to migrate the drives including data into the new NAS, rather than having to buy a NAS and additional drives before migrating data. New NAS should have 4 bays to leave room for expansion later on - and RAID 10. Primary usage is for backup of files, mostly photos and videos with an occasional video stream to TV. Power consumption ought to be kept low due to rising prices. I am an intermediate user with some skills, but I know I have never used all the features my Qnap offers.
For your needs, I would recommend looking into the QNAP TS-451D2. It is a 4-bay NAS with RAID 10 support and it is designed to be energy efficient. The TS-451D2 comes with a quad-core Intel Celeron J4025 processor and 2GB of DDR4 memory (expandable up to 8GB), which should be more than sufficient for your backup and media streaming needs.
One of the advantages of sticking with QNAP is that you can easily migrate your drives from your old NAS to the new one, assuming they are compatible with the TS-451D2 / 453d / 464. This should save you time and money, since you won't need to buy new drives.
In terms of features, the TS-451D2 comes with QNAP's QTS operating system, which offers a wide range of apps for backup, file management, media streaming, and more. You can also expand the capabilities of the NAS by installing additional apps from the QNAP App Center.
Overall, the QNAP TS-451D2 should be a good fit for your needs as an intermediate user who wants a reliable and energy-efficient NAS for backup and media streaming, while also leaving room for expansion in the future.