The AMEX Hilton Surpass gives 6 pts/$ (double the normal rate) for groceries. That's a return of about 3% given typical Hilton points valuation, and assuming you want Hilton points. AF is $75 I believe.

The regular Chase Freedom, as well as Discover, give 5% back in the quarters where groceries are the bonus category. No AF for either.

Are Trader Joe merchant gift cards available anywhere with a bonus category?