By the early 1980s Aeroflot had about two dozen types but of course they were organised into various units and departments. The unit that operated the An-2 wasn't the same as that which flew the Il-62. Likewise CAAC in China.
Commercially BA, Air France and Delta seem to have been the most diverse thogh Air New Zealand had quite a range after the 1978 merger, I'd need to check but I remember a lot of types from Islander up to DC-10.