I've calculated it out and I get more cash back with the blue cash annually since it gives 5% on gas and groceries.. Plus the fidelity one goes into a retirement account, not as useful especially since I don't use fidelity.
That Fidelty card is also not a real Amex so you dont get the great Amex customer service for disputes, etc. It's administered by FIA card services who I've learned from experience, has quite poor customer service and are going down hill.
Again, this Amex Blue cash has no annually fee so don't try to twist things to mislead people.
They are. If you were to use the Fidelity American Express card you would earn 2% from the first dollar. If I recall correctly, Blue Cash pays 0.5% on the first $6,500 (1% if you use it in the targeted categories) which means you have given up as much as $97.50. I cannot say if this is a worthwhile tradeoff for the opportunity to earn a higher rebate later, but it is straightforward to calculate if you know the total spend on the card, and the proportion in the targeted categories.