No annual fee is a good feature, but it does not make a product automatically cheap. You still need to check late fees, finance charges, cash advance fees, foreign transaction fees, and installment processing fees.
Compare whether the no-annual-fee benefit is permanent, conditional, or promotional. Some products have no annual fee by design. Others waive the fee only for the first year or only after hitting a spend threshold.
The best use case for no-annual-fee cards is long-term optionality: keeping a card open without paying for benefits you do not use. It is especially useful for people who want a backup card and pay in full.
Next step: Use the calculators and card database to test the idea against your own spending pattern.