Honestly I find you get more points not only based on doing the objective. But I seem to get more points by having good kill streaks and holding that kill streak for a longer time. Example killing 9 people without dying.
It also depends on the map as well. Such as crait for example. If you were on the defendibg team and use heavy class. Plant their rocket launcher deal above ground. So that it can shoot the objective. You would be surprised how much it earns you.
Though I always use assault class and generally get 20 to 30 plus kills without being a hero. You get less points when using a hero. Unless for example if you use Rey and use here show enemy skill. Every time a teammate kills one of the enemy you earn points and they rack up quick.