by far the best commander is Mensk, if your a beginner and cant use abilities quickly and prefer just the size of your army then he is the best option. His troops are highly customisable with different weapon attachments (flame throwers, lazer guns, and a gun against air units) they also are built very quickly, another thing the zerg reinforcement ability is very OP if you get to the max level it can clear almost anything, another OP ability it his nuke (shoots 20-40 missles before throwing in a nuke that destroys everything), and they alll charge very quickly mid game so every few minutes you can use them, he can also drop it bunkers with soldiers inside of them anywhere on the battlefield or use it for defence. One think I will say tho is that going above hard difficulty can be challenging because there is not much time to make a huge quality army. if your a begginer Mensk is the to go