For best performance, is it better to use a virtual IDE HDD or virtual SCSI HDD? If, SCSI, does it matter whether you use an BusLogic or LSILogic?
Go for the SCSI and LSILogic. IDE and BusLogic are for compatibility reasons. Like when you do physical2virtual...
There's a whitepaper from vmware showing the difference between LSILogic and BusLogic, which in my opinion is rather small: http://www.vmware.com/pdf/ESX2_Storage_Performance.pdf
Edit after like three years: With current ESX environments it's best to use the Paravirtual SCSI device.