There are a few that have already been mentioned on here.
Michael Robinson- Felt Allison got rid of him too quickly and he could have got him and Reeves working together
Gordon Smith - Always had time and space and scored goals as well. If he hadn't been injured we would have gone up as Champions in 85.
Kevin Horlock - great left foot and underrated- didn't he have a record in that every time he scored City never lost?
Finally someone who hasn't been mentioned so far, Joe Royle, linked up well with both Kidd and Tueart, sacrificed for Channon, who was decent but the wrong buy at a time when we needed cover for Colin rather than another forward.