Let's clear this up, for ESX/ESXi vmdk's can ONLY be stored on VMFS and NFS file systems - presumably what you're talking about is the underlying filesystems of the storage behind this. If this is the case what you'd basically saying is 'what sort of storage should I use' - and that's an extremely open question that you haven't provided enough information to help you with - so it'll be impossible to answer properly without extra constraints.
As far as I'm aware the 'best' mechanism for VM storage in terms of performance right now is by using FusionIO's PCIe-based flash storage set to emulate local DAS. The 'best' in terms of cheapest varies enormously based on volume from cheapo DAS to building your own NFS/iSCSI NAS/SAN box up to good value but still expensive FCoE SANs.
Basically we can't answer your question.