Currently on US itunes:

5. David Bowie - Space Oddity
9. David Bowie - Changes

12. Queen & David Bowie - Under Pressure
41. David Bowie & Queen - Under Pressure

31. David Bowie - Heroes (Single Version)
60. David Bowie - Heroes

38. David Bowie - Rebel Rebel


Peaks on the Hot 100:

"Space Oddity" #15
"Changes" #41
"Under Pressure" #29
Heroes - didn't chart
Rebel Rebel #64

I don't think Space Oddity will outpeak itself. Changes might, Under Pressure might. Heroes will probably chart for the first time, so it will def outpeak itself. And I don't think Rebel Rebel will chart tbh or if it does it will be fairly low.

Probably Heroes and/or Changes.

Heroes deserves it the best.