the schools machine is, as far as i know, running ok and I have built a new system for myself with 2 3tb drives and a 1tb I had spare in a NAS style case fitted with a ASRock J4205 all in one board.

Considering what I ended up needing (which I think is basically a file server), is it still best to go with unraid or should I try out freenas?

I liked the parity setup on unraid and the simplistic way you could add additional HDDs, but I am not sure how freenas works in comparison, but with freenas being free, it makes me consider my options.