A 4-lane SAS bus is faster than f/c and it's cheaper, 12Gbps Vs 8 Gbps (not that you'll get anywhere near that speed unless you have a hundred odd disks in your array.
Fibre channel is faster than iSCSI (assuming 1Gbps ethernet) but again you're going to need a lot of disks to get 1Gbps throughput, you only get 180 iops from your average 15K disk drive.