Hardware

Do not use ZFS on top of a hardware RAID controller which has its own cache management. ZFS needs to communicate directly with the disks. An HBA adapter or something like an LSI controller flashed in “IT” mode is more appropriate.
IOPS (Input/Output Operations per Second)

hybrid hardware (HBA) + software (ZFS) solutions is more flexible than a hardware only RAID solutions -> Software can be easily improve, enhanced or replaced entirely