Going by the numbers of those GPU's found in the APU's is deceiving. Much of what AM has done since a long time is rebadged their older harder with slight increments in clock speeds. If you must game on your system with an APU, you should aim at least an A8-7xxx or the A10-7xxx's. Processor wise they are not even worth investing in since a dedicated GPU would be severely bottlenecked.
If you're only asking which one between the three, then go for the A6-7400 but without any indication fo what you intend to do with your system and it's subsequent system's specs, we can't offer you much advice.