Sequential read speed or the mean data reading speed is the most important criterion of the high-speed operation of the SSD. The data from the SSD will be read much more often than written to it because the operating system stores the processed data in the RAM in most cases.
If you want the reading speed of the purchased SSD to exceed the speed of the classic HDD considerably you should choose the SSD with the reading speed of 200 MB/s or above. The additional increase in the performance will be achieved on the account of the data search (SeekTime) which is of much higher level with SSDs than any HDD.
The writing speed is almost as important as the reading speed. Also this parameter determines the performance of the SSD, however, as the writing to the disc happens not as often as the data reading and average user will find it subjectively difficult to distinguish between any speed above 100 MB/s and higher indices, except the cases when the SSD is used in a server, for audio/video recording, etc.
