Out of all the units that have been introduced to this game, my three favorites have got to be :
Flame Assault Vehicles (FAVs)
With the Vulture and Kondor being honorable mentions. I would love if this units would be re-introduced into War comander in Legendary forms or with new omega or elite version that greatly enhanced their abilities to the point where they are able to compete agaisnt faction units. The eras when this units were being used were, in my opinion, the most fun and interesting in the history of these game.