I tried to avoid Calibre for as long as I could. In my opinion, it’s way too opinionated about how everything is organized. Instead of working with you, the user, it forces you into line with how the developer thinks it should work. The developer is also kind of an ass to his community and, as a dev myself, I have some concerns over some of their choices.
All that said, I finally gave in recently and converted to Calibre because there’s nothing else that works as well. It’s too niche of a space for there to be much competition. To use it remotely - or, more accurately for my use, headless - the docker image I use sets up a VNC viewer to work with the application.
For actually browsing the content that Calibre organizes, I settled on Kavita. There’s no competition for Calibre’s organization but Kavita is easily the best content browser I’ve tried. If you’ve organized and tagged your ebooks with Calibre, it does a great job of making them available on the web and offers an OPDS server as well as the web viewer. I am more into ebooks than comics or manga but I have a few that Kavita also manages well.
There’s a lot of comments talking about used and refurbs. I personally use these types to get good deals but I also have a reasonably robust backup protocol. Not a full 321 backup but an appropriate level of risk for my needs.
My point being, if you go that route, they’re cheaper but the odds that one dies on you might be higher. Make sure you manage your backup strategy to a risk value you’re comfortable with.
That said, I’ve also had great experiences with serverpartdeals. I’ve also used diskprices.com to find deals.
Things to consider are noise, temps, power-on time, etc. For myself, temps are fairly consistent in my case and it’s in a closet so I don’t care about noise. I also don’t need particularly fast access on the HDDs (I use an nvme cache strategy as well) so I can pretty much use whatever. Your needs might differ.