In ESX 3.x there are only two different type of virtual SCSI adapters: Buslogic and LSI Logic (new from ESX 2.x)
The backend for Buslogic / LSILogic is almost identical, with very minor differences due to the hardware specs being different. The differences only apply during device driver loading, and should not affect I/O speed.
The real reason for two controllers is driver support. Older OSes have default driver support for Buslogic (e.g. Windows 2000 install CD), newer OSes do not have Buslogic drivers but do have LSILogic drivers (e.g. Windows 2003, 2008 install CDs). Pick the controller for which it is easier to obtain a driver for the guest.
Windows 2000 has by default the BusLogic driver, and Windows 2003 the LSI Logic.
For Linux in most cases, VMware recommends that you use the LSI Logic virtual SCSI adapter with all Red Hat guest operating systems. However, ESX Server 2.5.2, 2.5.3, 2.5.4, and 2.5.5 support only the BusLogic SCSI adapter. VMware provides a separate BusLogic driver for Red Hat Enterprise Linux 4 Upgrades 1, 2, 3, 4, and 5 (see http://www.vmware.com/files/pdf/linux_install_config.pdf).