It may not be buzzy but I really like the AmEx Everyday for a secondary card. No annual fee and it gets you 2x Member Reward points at grocery stores. MR points can not only be transferred to Delta for SkyMiles but also into the Air France/KLM Flying Blue and Virgin Atlantic programs, both of which sometimes offer cheaper award redemptions on Delta flights/routes than Delta does. (And once a year or so there tend to be useful 20-30% bonuses for transferring into those programs)