Well, the 3470 has a faster clock, that overshadows the architectural improvements of Haswell over Ivy Bridge. It really doesn't matter that much. If I put you down in front of two systems with the different processors, you would never be able to tell which is which. The 3470 is also a lower TDP processor, that's good, but Haswell should use less on average.
What sort of boards are you looking at? What are the price differences? Lots can go into the decision if you are looking to buy one.
That said, it's generally better to go with the newer architecture.