Advice needed on motherboard/processor

[Splat_ed]

Afternoon all,
I’m in the process of designing a small home server and been reading around. I’d like to get some advice on the pros and cons of some of the options.

Server functions:

• File server (Mainly a large movie collection but also photos and work-related files...)
• MinimServer (for internet radio)
• Plex server (for all those movies...)
• Ubiquiti UniFi controller
• Ubiquiti MFi controller
• Ubiquiti UniFi camera controller and storage
• VPN / ownCloud
• Other (to play around with & learn)

My initial thought is to use Ubuntu and KVM to set up VMs for these. (Not done that before but willing to learn)

I’ve already got a few spare pieces of kit lying around which I could use to save money on.

The options I’ve been considering:

• AMD e450 (Asustek E45M1-I deluxe) (already have, currently unused)
• Intel i3 3.5GHz (Asustek Z87I-Pro) (currently have, in use as HTPC, can repurpose)
• AMD Ryzen (from reading http://blog.patshead.com/2017/08/building-a-low-power-high-performance-ryzen-server-to-host-virtual-machines.html)
• Proper server hardware (not sure what)
• A pre-built NAS (such as Asustor, QNAP etc)

My main goal is low-power. Noise is less important as this will sit under the stairs. It will need to be easily administered remotely. I’d like to keep the cost down (dictate from the wife!)

Obviously, using the gear I’ve already got will be cheapest, while proper server hardware gives access to easier remote administration but requires ECC Memory (and greater expense). Would the first two have enough power to get the job done? What would people recommend?