[Build Help] ATX - Future expandability

Hi guys.
I’ve been lurking for a couple of weeks now and wow, this place is a great source of information.
Very well put together!

Anyway, I’ve a home made nas with an ITX SoC mobo and I’ve come to a point that it’s not enough anymore and I’ve started to look at upgrading it to an ATX case running unRAID.

The problem? I’ve a tendency to dive a bit too deep into specs and between this place, r/homelabs and r/datahoarder I’ve found myself lost.

I’ve decided (for now) that my case is going to be a Fractal Design Define R6C, because it fits my current needs and looks good (GF aproved), but I’ve a hard time choosing all the other hardware, except for harddrives.

Budget: 3-400 USD

What I want and going to do with it:

  • Plex - Main purpose. Today i direct stream 4K with no issues, one viewer
  • unRAID - with a few dockers
  • 1-2 VMs - I like to learn and fiddle with stuff so I’d like to have the option / capability for it, but as of now I wont have any other “use” for VM capabilities.

In the future I’ll be purchasing a house where I know I’ll be home automate the shit out if it and also run surveillance, so having the option of upgrading the existing hardware later on would be a + for me.

Also just a side question, what would be best?
Running the harddrives on the SAS/Sata ports on the motherboard or get a controller?