The Capital One Venture Rewards card gives me 2% back on all purchases (I'm in the US). It comes with a $60 per year fee. So, if I spend more than $3,000 on the card over the course of the year it's a net positive. Now, they have access to all of my purchase data but I get around $700 every year to spend on travel. I've weighed the costs/benefits and it's worth it to me.