No annual fee for Citi Double Cash. I have it but it's sock drawered cause I get way more value from travel cards.
Pretty much any card with a 50k points sign up bonus is worth $500-1000 easily. Chase Sapphire Reserve, Citi Thankyou Premiere, Capital One Venture. If you don't want to pay the annual fee, get the bonus and cancel the card before the first year ends. Then move onto the next card. Just go down the list of top travel cards at Nerdwallet or thepointsguy. "Churn". These cards come with benefits like lounge passes (free booze and food at airports), TSA-pre reimbursement (shorter security line, don't have to take off shoes or take out laptop), travel credits, primary car rental insurance, many more. Read up at ThePointsGuy, Flyertalk, etc.
Cash back cards generally have no sign on bonus or a paltry one. The big money is in the sign on bonuses. For example, spend $4000 on Citi Double Cash and you'll get a measly $80. Spend $4000 on Chase Sapphire Reserve and you'll get 50k ultimate rewards which are worth about $1000 in airfare. Even after you get the bonus, points are worth 1.5 cents a piece but you'll get 3x points on dining/travel expenses. So if you spend $1 at Wendys, you'll get 3 ultimate reward points which are worth 4.5 cents. Compare that to the 2 cents you'd get from Citi Double Cash.
If you don't travel then a 2% cash back card is better than nothing I guess. But if you don't travel, you're not living.