IMO, Savage Worlds is the stronger system for two reasons:
1) Better support. Savage Worlds has tons of books for different genres (fantasy, modern, sci-fi, etc.) as well as licenses for some settings (Solomon Kane's RPG license is the first one that jumps to mind right now).
2) The game itself doesn't tend to very high numbers results, leading to quicker die resolutions that don't break the game flow as much. One problem I used to have with d6 was dealing with scores over 7D or so; Say you have a hero with about 10D in a firearms skill; they can pile off four or five shots in a round, leading to rolling about 30 dice (10D shooting five times = five pools of 6 dice in a round to figure up).
Where d6 shines, though, is in making adventures for one or two players. Because of the way multiple actions work in d6, you can fire the grapple line, climb the AT-AT, blow a hatch, toss a grenade, rappel down, and run away, all in the same round -- and still see a chance of success.
Savage Worlds to me, though, is the better game, despite the more mundane limit on one or two actions a round it puts on its PCs.