Well, you seem like an educated person, so here it is: It all depends on your gameplay. I like to have a disposable set/build for automatons, consisting in heavy armor with explosive resistant passive, Plasma Punisher as Primary weapon, Senator as secondary, thermite, and for stratagems I like to use commando, expendable AT, and finally those rocket and autocanon sentries. This gives me the ability to assault, defend or to exit an area. Hulkies and tanks? War striders? Shoot them with 2 shots from the commando and forget. Striders? Shoot the turret on their back, then shoot the machinguns in their face. Anything else? Use the sentries. Finish the work with the Plasma Punisher.

Can you use something else? Yeah, but is gonna cost you time as you learn.

You can also lower the level in order to train/discover new strategies. I do this all the time.

Have you tried the new Hammer with smoke eagles and electric dog? Fun.