There has to be some kind of indication as to your budget, otherwise it's very difficult to recommend.
Here are the questions you need to ask/answer:
- Will your NAS be used by just you or multiple people?
- If multiple, how important is it to isolate their files?
- Will you use it over local network only or want to access it from anywhere in the world
- How much storage do you need? Do you see it growing consistently such that you keep adding more every year, or do you think you can get 16 TB now and make it last for 5-6 years?
- Is it absolutely critical that you don't lose any of your data? Or you'll keep important documents on the cloud as a backup and some possibility of data loss from the NAS is acceptable?
- How much time/effort are you willing to spend on setting things up?
- Do you see yourself running other services on it, like a database, bot scripts, etc.?
The options you have are
- Build your own using a Raspberry Pi or any other SFF build or old PC which you can get for cheap (like a Dell Optiplex from OLX)
- Buy a proper NAS solution from brands like Synology, Asustor, WD, QNAP, etc.
If you are comfortable with Linux and are ok spending some time learning and building a NAS, go for the first option, it will be cheaper. It will also you the greatest flexibility in terms of hardware/software you want to run. However, in case you go for NUC or Raspberry Pi, you might need additional hardware like Disk bays, Powered USB switches, etc.
If you see your data needs growing continuously, or your data is critical to you and loss is not acceptable, then go for a 4-bay NAS, which you'll be able to setup in RAID to guard against accidental data loss.
If you have multiple users and you need isolation, something like Synology will offer you those features out of the box. You will also be able to assign quotas to each user.
If you need internet access, Synology provides a tunnel based access out of the box. For own setup, you'll either need a dedicated public IP (not necessarily static IP, but dedicated IP, i.e., you're not behind ISP NAT), or will have to fiddle with an ngrok like setup. Keep in mind though, that Synology does not give you the option to use your own domain, just a subdomain on quickconnect.to.
If your needs are limited, and you just want something quick and easy to setup, something like Synology DS220j will offer the greatest value for money.
So here's my recommendation:
- Need complete control over setup, don't mind spending time, and want the possibility of expanding it into a home lab later: Go for a Raspberry Pi 4 or SFF build
- Need lots of storage but don't have a huge budget/don't need to run lots of services: Asustor AS4004T - 4 Bay NAS
- Need lots of storage and want to run services, but don't have a huge budget right now: Synology DiskStation DS720+
- Don't need lots of storage and want something not too expensive and easy to setup: Synology DiskStation DS220j
- Need lots of storage, possibility of running more services, easy to setup, and budget not an issue: Synology 4 bay NAS DiskStation DS920+