It really depends on what you want with your SSD. On paper the SF-1200 looks more stable with its DuraClass technology (RAISE and DuraWrite)
features not available to other SSDs while the RealSSD controller is not such "new high tech" but more raw muscle power
Currently the Sandforce SF-1200 SSD thats out are the Corsair Force (limited availability still) and the Vertex 2 that shows some shops getting this on Friday and next week. Between these two I see basically only the warranty thats different. 2 years for the Force and 3 years for the Vertex 2 so I would recommend Vertex 2 if we talk about these SSD but prices is another thing that might prove deciding in the end.
For RealSSD C300, this will need SATA 6Gb/s or else it will run slower both on R/W, around 265MB/s Read and 215MB/s Write according to the Micron site for 256GB model, however RealSSD C300 is usually cheaper and offers 3 years warranty, extra 56GB space with 256GB model compared to the Force 200GB model, however prices might change as the various Sandforce brands comes onto the market. It should be noted that RealSSD C300 has a
bug with trim affecting speed over time but fix should be out via firmware upgrade this month.
Crucial RealSSD C300 - 355MB/215MB sec Read/Write (on SATA 6Gb)
Corsair Force SF-1200 - 285MB/275MB/sec Read/Write
ADATA S599 SF-1200 - 280/270/sec Read/Write (286/287/sec R/W speed with ATTO on benchmarkreviews.com)
Personally I have my eyes on a Sandforce SF-1200 SSD but others might choose a RealSSD C300 instead
