i'd get the i7. there isn't enough of a bump in haswell's performance to justify the higher cost of the motherboards, and chips, it also is very iffy you could get much of an overclock out of one. IB is late in it's run, the chips tend to overclock a lot better then they did. stick with the IB.
For gaming, there will be little difference in performance. Few games can use more than 2-3 threads.
I would favor haswell, primarily because the Z87 chipset that you need is better than the z77 it replaces.
Better is really subjective. Z87 doesn't offer me anything I really need that Z77 already does not offer. Going forward the number of games that can use more threads will go up. Crysis 3 and BF4 are just the beginning.