Are you looking for a powerful NAS with lots of features? One of your options is QNAP, and if you have limited space but still want to have a lot of drives, the QNAP TS-669 Pro is an interesting option. It's based on the Intel Atom D2700 and equipped with 1GB of RAM, and while it isn't cheap, it's a very fast and comprehensive solution.
Let's get one thing out of the way. The QNAP TS-669 Pro costs an average of £870, so it's definitely not the cheapest NAS out there. This model is a sibling of the TS-869 Pro (£944), TS-569 Pro (£800) and TS-469 Pro (£672) with room for eight, five and four disks. The price per disk space is as follows: £118 for the TS-869 Pro, £145 for the TS-669 Pro, £160 for the TS-569 Pro and £168 for the TS-469 Pro. None of these are very cheap, but the eight-disk version is £50 more than the four-disk one. If you expect your volume to grow quickly in the short term, then investing in the larger version could be worth it.
These devices are aimed at business users or very demanding home users. Generally speaking, QNAP network drives are typically more expensive than average, but you do get quality in return. For example, the exterior is a sturdy, metal chassis with quality disk trays that will fit both 2.5in and 3.5in disks. Each disks can be individually locked with a key.
On the front there is a display that is very easy to read. It doesn't only show the system status, it also allows you to set the drive configurations during installation. This is practical for when you don't have access to a computer. There is also a USB port on the front with sync button, which quickly lets you make a back-up or transfer photos from your camera to the NAS. It's too bad it uses the older USB 2.0 version and not USB 3.0. You can read the rest of QNAP TS-669 Pro: pricy but good on Hardware.info.