Look into ata(4) for list of supported ATA chipsets. Usually the best choice is chipset built-in controllers. If you need external/additional, there are a lot of cheap JMicron, SiliconImage, Marvell, Promise based products.
If you need higher performance, I would recommend you to look on siis(4) and ahci(4) drivers at FreeBSD 8-STABLE branch. But it is not about FreeNAS.