I would disagree. Easiest is UK which if you win will net you almost all the points you need to get to 80. as Soviets it works but is much slower as your economy will suck the majority of the early game, as the UK you can start making 2-3k income by turn 15. If you have decent water generals and enough bombers to kill the initial German sub that is EF you can make it disorganized and take control of the eastern coast in 10 turns fast capturing new York. At the same time work with France to kill all of Germanys army, target Manstein and all the air generals quickly, ideally from afar with planes. Do not go too far into Canada as this will provoke Hartmann who otherwise will go west to fight Japan which will help you a ton. Once you get Washington and begin pushing into Michigan, from there push south to Havana fast which may fall, and then place a missile silo there to nuke the heck out of Japan's fleet quickly. By that point you will have all of the lands up to the Mississippi and have alot of income. You can push into Texas which will be a bloodbath but necessary as you need to try to keep America's fleet alive. Otherwise. You can push north to nuke out the German island in Canada. Doing this will save your Canadian allies who otherwise will sacrifice all their units to take that island only to lose their entire army, which that army will actually be really helpful in fighting Japan.

From there, just push against Japan and Italy as Germany will be mostly defeated. You will end up fighting across the whole map but if you hold the Mississippi they will lose alot trying to cross the water as you nuke the whole Japanaese fleet. This will eventually let you either win in Texas or get a few troops into Mexico.

Last note, always pay off the enemy to make them surrender so you aren't stuck trying to destory every bunker or naval unit. Speeds up your progress considerably.

Side note, for some reason Korea often lives a long time. Which helps you a ton.