I really like this kind of subject so i created 1 name your 2 favorite type of units for Navy, Ground force, Airforce (missiles count as airforce)
Ground units:
1: Special Forces: basically the most over power attacking unit in the game easily tops my list by far
2: Recon Vehicle: i know you might think this dude i just the worst player ever but if you notice they can also air assault after being upgraded meaning i can stack those with SAS and still have the power to air assault and even more attacking and defending power
Air force:
1: Stealth Strike fighter: it is over powerd
2: heavy bomber: good for infantry units if not using strikes
Navy:
1: Destroyer: takes out subs the best and is almost as good as cruiser in dmg to ships
2. Ballistic Missile Subs: shoots missile whats not to love?
Ground units:
1: Special Forces: basically the most over power attacking unit in the game easily tops my list by far
2: Recon Vehicle: i know you might think this dude i just the worst player ever but if you notice they can also air assault after being upgraded meaning i can stack those with SAS and still have the power to air assault and even more attacking and defending power
Air force:
1: Stealth Strike fighter: it is over powerd
2: heavy bomber: good for infantry units if not using strikes
Navy:
1: Destroyer: takes out subs the best and is almost as good as cruiser in dmg to ships
2. Ballistic Missile Subs: shoots missile whats not to love?