There's a neat set of pros and cons for each unit type in the Battletech world.
Mechs are high impact, high value units. Like cavalry they are individually powerful but costly and must be used correctly with the right support to live up to their potential.
Tanks on the other hand are cheap and efficient, the workhorses of the military. Like spearmen. They are the smartest choice when garrisoning the vast territory you control. This can be further split into Wheeled, Tracked and Hover armor and the same with VTOL vs traditional Aerospace but yeah, lots of nuance when you dig into it.