Depends on your individual spending habits and if there are any limits to how much you can get in cash back. (i.e. some only consider 10,000$ in purchases, others cap out at 25,000$ etc.)
The annual fee pays for itself if you rent 1 car for the year or leave the country on a trip. Never hurts to have multiple layers of security and these cards are considered 'World' cards that have a handful of features as incentives to use them (Car Rental discounts, rental insurance, health insurance, double the manufacturer warranty on items purchased, flight delays, cancellations, reimbursements, preferred hotels, etc).
Don't focus solely on the cashback bit, but the whole 'value' of the card to you.
for the fee to pay for itself, you'd need to put about 2475/yr through the card.
add up your gas and groceries, and if they're over 2500$ for the year, the cashback you get breaks even on the cost of the card. This number gets bigger as the discount changes to 2% for pharmacies and 1% everywhere else, or whatever the structure is.
At least with cash back rewards cards it's straight forward, the money adds up over a year and gets added to your card on your anniversary date. Other reward cards where you collect points might make it difficult to collect or might not have a points system that's worth it (i.e. less than 1% or something silly)
edit: forgot to add, if you add recurring bills, you get a 2% bump, so your cell phone, cable, internet bill gets you cash back as well. every little bit adds up over time, and if you're paying it anyway, why not?
4 months of gas ($200), grocery ($500), tv/internet ($120), pays for your card. Assuming these are your expenses for example. ymmv