What do you mean by fastest? What do you do with your computer? What do you want to accomplish? Are you only interested in SATA 3 6Gb/s ssd's designed for consumer use or are you interested in other types?
The fastest ssd's are enterprise level ssd's designed for extremely heavy duty professional and scientific work.
For SATAIII (6GbPS), definitely the new Samsung 840 Pro or the Intel 520s.
For SATAII (3GbPS), you're going to top out round 260-270 read/write. I like the Crucial M series and the Samsung 830s for those builds.
PCI Express options definitely have a higher speed capability but the cost is ridiculous.
You would be better of working with a motherboard that supports SSD RAID configs and us 2 SATAIII drives.