I'd rather them have a movement command than a fire at my target command; cause that means we have to take our aiming time to pick their targets for them and then we gotta aim back at what we wanted to shoot at.
Instead of a fire at my target command, I'd rather have some sort of a "fire at" setting we set up somewhere. The settings could be like: default - fire at closest target, stopped - fire at closest target that hasn't moved for some number of seconds, specific - fire at the closest SPG-AFV-TD-LT-MBT (the inf would fire at any AFV in range first before a LT that was closer to them, and players could set their own class order, that would be my order), and specific stopped - fire at the closest SPG-AFV-TD-LT-MBT (same as last one but goes by stopped as well; as in let's say there 1 enemy of each of LT, TD, and MBT in their range (3 enemies in total)... the MBT is stopped, the others are still moving... the inf will shoot the stopped MBT first... but if either of the others do stop, they will shoot the others by the order)