A53 would be nice indeed. I think CPU core count makes very little difference in price, because it's such a small portion of total chip space used. 64 kB L1 and 512 kB L2 (configured in such a way CPU can use it) would be very nice too. I hope it also has 2 GB RAM, at least as much graphics performance. More wouldn't hurt, but Videocore 4 is pretty ok as it is.

USB3, SATA and gigabit ethernet. Or at least 1 PCIe lane.