Starflight 1 and 2 (Trade Routes of the Cloud Nebula).
(Yeah, my standard answer to everything.)
Better graphics, nicer controls (mouse+keyboard instead of just keyboard). Although, to be fair, the Amiga versions were released 2 to 3 years after the respective PC versions (1986 PC, 1989 Amiga for Starflight 1; 1989 PC, 1991 Amiga for Starflight 2, I think).
p.s. I don't care whether anybody cares.