Honourable mentions to 2001/2, which was great fun, and 1980/1, which featured that gripping recovery from the foot of the league table and the two wonderful cup runs. I also loved the 1988/9 promotion campaign, when I went to most of the southern-based away games from university and we saw the initial flowering of a group of outstanding players fresh from the youth system, with whom I especially identified because they were my contemporaries and I'd watched their progress in the youth and reserve teams.
I'd go for 1976/7, though. It was my first full season watching with my late dad, and we had a better side than City had at any point until the 2010s. As a young boy, I found it thrilling to turn up to watch that team full of international players win nearly every week in front of home crowds that averaged over 40K per game, and were invariably vocal and raucous, too.
Unfortunately, that group of players never quite reached its potential, IMO. The loss of Colin Bell the previous season was arguably the difference between it going down as a 'nearly' team rather than a great one and we didn't get the transfers quite right to enable us to build on that runners-up spot in 1977. Nonetheless, that team and players in it such as Corrigan, Doyle, Donachie, Watson (my particular favourite), Hartford, Barnes, Tueart, Kidd and others claimed my heart in a way that no subsequent team quite has and instilled in me a love of this beguiling but daft institution that is MCFC.