For SSDs that have been released in 2012 or 2013, then it doesn’t really matter, almost all SSDs perform similarly in real world applications.
If you are booting windows or running games or doing some work on virtual machines, all will perform the same, and no one will notice a difference in speed, since all today’s SSD are fast enough to saturate what the processor can handle.
Many SSD sellers advertise the SSD’s sequential speed, which is always around 450~550 MB/s however, in real world, random access speed is what really matters and what makes SSDs much faster than 10,000rpm HDDs, and SSD manufacturers do not always advertise those, so you will have to do your own research for finding review of different SSDs random access speeds. I still stress the fact that all today’s SSD random speed are fine, will perform similarly in real world applications.
Other important aspects of choosing an SSD are power usage and reliability, and for those also, you will have to look on-line for reviewing websites that have tested the real power usage values, and you should lookup the SSD’s manufacturing company reliability track record.
Another thing to note when comparing power consumption is that idle power consumption is the main thing to worry about, since SSDs are so fast that they usually stay idle for over 95% of the time even in the event of data access.
For reliability, as of 2012: Intel, Samsung, Crucial, Plextor, and then the rest.
External link for benchamrks of file copying and game load times: