Each unit has it's ups and downs. For example: The Riflemen are the weakest but their numbers and prices make them great for rushing the enemy. Tanks are the strongest but their prices and cool-down make them hard to get more than one or two. Snipers are good for long distances but are easy to kill once the enemy have gotten close enough. There's not really a "best" unit, it just depends on the type of strategy you prefer. If you wanna rush the enemy use riflemen and (forgot the name) the guys that are good at attacking entrenched units. If you want to defend use snipers and machine men behind trenches and barricades.
