Depends on what you buy and what kind of rewards you want. For example, I haven't flown in 8 years so miles/free flights are worthless.
What I currently use: Amex Blue Preferred. There is a $75 annual fee. The Amex Blue has no annual fee. Perks to the preferred are 6% back on groceries up to $6k, 3% on gas, 1% on everything else (the Amex Blue is only 3% on groceries). We're a family of 3 and don't spend $500/month on groceries, so I max out the groceries reward by buying gift cards to places I would otherwise be shopping at (Home Depot, Target, Lands End,
Amazon, Disney, Gap, etc.) Then I'm getting 6% off the gift cards plus fuel perks. Amex has amazing offers. I've probably used $150 worth of offers since November. Last week I got a $100 amazon gift card at Staples for $75. I also saved $25 off at Amazon, $15 at Costco, > $50 on gas at BP, etc. These offers plus the 6% back on groceries make the $75 fee worth it for me. Plus when I signed up I got $150 reward so my first two years were basically free.
For other categories that only earn 1%, I am using the Capital One card with no fee that gives 1.5% on everything.