Although this is my least favorite set ever, I still have a Top 5
The pre-steriod HR leaders on one card. From an era when 50 HR's were a big deal and 60 was mythical.
The baddest pitcher in baseball, at his peak, and in full windup.
The first corrected error that I ever owned. It's kind of weird that Topps neglected to change teams on so many players that changed teams before this. Yet when they decide to do it, they screw it up.
Another intimidating force on the mound. Is he really standing on one heel?
When I was a kid, Rose cards were like Mantle cards are today. His last card as a Red (at the time) and a nice action shot.
Honorable Mention:
Ozzie Smith (boring card that didn't really get much attention until people started realizing he was a HoFer)