I think the AmEx Blue Cash Preferred is a no brainer. 6% back at grocery stores (capped at $6k and then the bonus drops to 1%), 3% back at gas stations, and some other sometimes interesting categories. Annual fee of $95 (waived the first year), and $250 statement credit on the first $3k, although that's been higher in the past.
So if you spend at least the $6k at grocery and $1500 on gas, that's ~$650 the first year.
I keep it around because the grocery bonus alone covers the annual fee for this and two other cards.