What hardware is best for rendering?

So I am just starting to render scenes and was wondering which of my PCs would be best to render on (and whether or not to use gpu rendering).
Laptop- i7 4720hq, 16gb ddr3, gtx 860m 2gb
Desktop- q9400, 8gb ddr2, r9 380x 4gb
Server- dual e5640, 16gb ddr3, (and am planing on swapping my 380x to this machine)

What would be the pros and cons of each machine, or should I try and build a miniature render farm with these machines? (I have a gigabit network)