Paul Heyman is already the greatest manager of all time, based solely on his accomplishments of managing world champions, but I wanted to point something else out.
This is a list of every world champion he's managed, along with the length of the reign;
1. Brock Lesnar - WWE champion 84 days
2. Big Show - WWE champion 28 days
3. Kurt Angle - WWE champion 81 days*
4. RVD WWE champion 22 days
5. CM Punk WWE champion 146 days*
6. Brock Lesnar WWE champion 224 days
7. Brock Lesnar WWE champion 173 days
8. RVD ECW champion 21 days
9. Big Show ECW champion 152 days
10. Brock Lesnar Universal champion 504 days
11. Brock Lesnar Universal champion 156 days
12. Brock Lesnar Universal champion 28 days
13. Roman Reigns Universal champion 891 days"
*denotes time associated in role, either through joining or leaving title reign before it either began or ended
"denotes combined championships in singular timeframe
That's 2510 days so far as the manager of the World champion, which comes out to close to 7 years. We're almost getting into Bruno territory as far as anyone directly associated with a world championship is considered.