SUpreme Commander. All three campaigns. No losses. How? Well,as an RTS,there's a surefire,two step way to never lose.
1) Secure as many resources as possible. In Supreme Commander,resources come in as Mass (extraced from key positions on the map) and Energy (produced from Reactors,which are built by the Engineers and ACUs). Expand quickly,take the resources,and go to step two.
2) Turtle up. In SupCom,you're given immediate access to defensive structures to help defend your primary base and earlier outlying assets. By the time you hit Tech 2 (Usually within five minutes for me,which is fast in SupCom time) you can build Shield Generators,which block a significant amount of incoming fire,so long as it isn't a Strategic Missile (Nukes).
To make this even more viable,there are Tech 2 Point Defenses (anti-surface) and Tech 2 Tripple A (Anti-Aircraft Artillery),and Tech 3 SAMs (Surface-to-Air Missiles). And,as a key feature to SupCom,resources stream. You get income per second,and you can run for profit,or drain. If your economy is strong enough,you can build everything in the game for profit.
Utilizing my two-step plan for domination,I turtled up,made artillery (Tech 2 and 3),and made armies of 200+ land units,supported by bombers,fighters,and gunships of near equal numbers. For navy,either flotillas of 50+ subs,or a cohesive armada (25-35) of subs,cruisers,destroyers,battleships,and gunships (which are seperately 30-50).
However,the challenge of the campaign is doing this while your enemies are already well-established. And then defending the outlying outposts without mobile forces. It's a nightmare,especially since Mass Fabricators are EXTRORDINARILY eniffecient (Tech 1 requires around 100 energy per second to pump out a pathetic one mass per second. The Tech 3 verisons are more efficient,at 1500:24)
Also,shields eat up a lot of power to run,artillery takes power to fire,and for heavier pieces,to acquire a target. The main challenge of the first game's campaign is surviving long enough to get a good economy rolling.
TL;DR: SupCom 1's "Victory Equation" is Econ and Turtle to Steamroll,often with Experimentals (Insane Superweapons)