'Contact' perhaps as it was the first one ... I liked 'Comet' too ...
btw Sagan helped to prepare five NASA missions, one of the Mariners
and lately Galileo too ... his fiction is often solid science ... ;)
In Germany a series was broadcasted on TV 'Our Cosmos' (12 parts?) ... theme
was composed by Vangelis ... not available anymore unless on Cosmos-DVD ~*~