I’ve been running a 12 bay nas for 8 years the only drives I have had fail have been Seagate drives.

I now use WD reds and lately due to their very good price point on eBay Toshiba drives.

Although the Toshiba drives do seem to be slightly noisier so depends where your server is located.

I switched from Calibre to Ubooquity.

It seems to handle all files types, with an easy setup and nice interface.

There is a default comics section that you can use for your cbr and pdf files.