NFS is very performant in closed network and it's simpler than SMB to setup, SMB share has more configuration about access and permissions and it can be accessed by windows OS.
If you need a simple share that can be accessed only by known machines, I'd recommend NFS especially in LAN network has very good performance. SMB is more secure but it need more configuration ( nothing impossible ) and it can be accessed by almost all operating systems, it's a must if u need to access it via WAN network.
In your case I suggest NFS but if you have in mind to expand his functionality in the future then go SMB.