Turbo link is more user friendly and has very good tech support. Downside is update rate.
Directscan isn't as user friendly. Upside is update rate. In a 12 second run you get approx 200 frames of data. Turbolink with fast update would only get you about 16 frames.
I wanted to see what my car was doing through the entire run, so I went with direct scan. Go to gnttype.org and look at the scan tool comparison chart.