He had a Decent to Good test record as captain. But not earth shattering. Ganguly's India beat the Aussie team; which is one step better than Imran's Pakistan not losing to Windies. Doesn't make him an ATG skipper either.
Imran had too much say in team selection. Won't happen anywhere outside Pakistan. He was good for his country for the times he lived in. That's all. Don't take him anywhere near the ATG teams as captain. Of course, he is in the first or the second team as a player for sure.