I got the OTC SPX scan tool myself. I did get it before I knew about Forscan.
The SPX is probably slower and laggy, and expensive. However, I now that I have it I prefer to use the SPX rather than a laptop to do scantool functions, especially live data and recording of live data.
A good scan tool is useful when it can record data before and after a trigger point. SPX has the ability to record and save the before and after data when a fault code is set, or you can set your own trigger point.
Forscan is very powerful and may be able to do all this. If you don't mind setting up your laptop in your car, it may be worth seeing if and how it can record certain engine parameters. If Forscan is unable to record past and future data from the trigger point, this can be a valuable consideration for diagnostics.