In all likelihood, there will be no practical performance difference between these. If you look at real-world benchmarks (which are hard to find for SSDs, usually you just see some IOPS and sequential throughput numbers), you will see that all SSDs perform pretty much the same, from ancient Indilinx drives to the pinnacle of PCIe SSDs. The main difference between SSDs is lifespan, and even that is moot since anything with an Intel, Sandforce, or Marvell controller will outlive its useful life by a huge margin.
So there's no practical difference between these except for the price. As for the theoretical performance difference between them, that's most likely just a result of firmware throttling. Sandforce provides firmware with fully unlocked performance to OCZ, and that's the firmware they use in their Vertex line. Agility gets the same throttled firmware all of the other manufacturers on the market use.
I'm not sure on the Solid, though. As I recall, Solid 1 used the JMicron controller and Solid 2 used the Indilinx controller. Now that there's three drives with the same controller, there might be three different firmware revisions, but I think it's more likely that the Solid series will end up using the subprime NAND that was causing all of the fuss with the Vertex 2 a month or two back. It shouldn't have a significant effect on practical performance or lifespan, but if the price were the same, the Agility and Vertex would certainly be better drives.