Still the choice of vmfs vs NFS is under your descretion.
For SAN, EMC has this SRDF mirror (Symmetrix) and Clarrion for considerably small storage. And EMC Centra for NAS.
With NetApp same storage (FAS) can be used for SAN or NAS (Again advantageous here, if you plan to change your environment from NAS to SAN in a future point of time you can use the same storage unlike EMC).
Both block and file level are equally competent, I have seen block level is comparatively better as compared to file level, But you can put larger number of VM on nas datastore, it also gives you flexibility while managing large number of VM as compared to block level, where you can’t mount data store on any unix box.
I suggest you to go read NetApp TRs and chose best possible solution for yourself.