A multiband compressor will really squash the dynamics of a sound, it's good for tightening things up in the mix (supersaws, etc.) Dynamic EQ is useful to boost frequencies that you want or to reduce frequencies you don't want. These boosts/reductions are only applied when they cross a threshold that you set, as opposed to being set in stone like with a normal EQ. I always use a MBC on my master chain but prefer to use dynamic EQ only in the mixing stages. hope this helps!