Your storm may be better at grinding. But I was told it was a fact that the Tank will do you better in the story missions.
My first real ship was a storm. I did love it. But I was limited on how long I could stay in battle when facing multiple Enemies. I picked Tank mostly because of it's capabilities to kill more lesser odds. It is not my choice on what ship others pick. I am just saying tanks will do you better in story missions. Alot of people I play with who use storms only said that they used tanks only in the story missions and then bought the storm afterwards.