This whitepaper by VMware Technical Marketing really is a great comparison between the most common storage protocols that are being used with vSphere Infrastructure. When designing your virtual infrastructure it is important to know what the characteristics are of the various protocols that can be used to connect your ESXi host to a shared storage environment.
This document describes and compares the following storage protocols:
* iSCSI
* NFS
* Fibre Channel
* Fibre Channel over Ethernet (FCoE)
The whitepaper can be found here.