Well, I owned an X25-M 80GB for two years that never let me down, a Vertex 3 120GB for 2 weeks that died, and now an M4 128GB that is running well.
According to benchmarks, the Vertex 3 was fastest, the M4 next and finally the X25-M. For my real-world use they all felt exactly the same. SATA III makes very little difference unless you are reading/writing very large file sizes, so the most important thing is latency. What the X25-M loses to the Vertex and M4, it seems to make up for with much lower latencies.
X25-M
Pro's: Low latency, bullet proof, great software (SSD Toolbox) and support for multiple Operating Systems.
Cons: SATAII read speeds and sub 100Mbits writes
Vertex 3
Pro's: Very fast read and writes.
Cons: Dismal life expectany.
M4
Pro's: Almost as fast as the Vertex 3. Appears to have good reliability.
Cons: Lack of software for manual TRIM or Secure Erase.
Out of the 3, I actually prefer my old X25-M. As performance feels identical between all of them on a SATAIII mobo, the only seperators are reliability and software. The Corsair is much more likely to fail than the other two, yet Intel has by far the best software (manual TRIM, Secure Erase and diagnostics are easy). The M4 may be faster on paper, but it does not feel anywhere near to a generation infront of the X25-M.
So, my advice for anyone looking for a good value SSD is to buy a used Intel X25-M. They can be had very cheap, are plenty fast enough for an OS drive, and have cast iron reliability.
