Ehh, it's up to you. There's not going to be a huge difference between Haswell and Ivy bridge unless they happen to have switched back to solder instead of TIM under the heatsink, but that only matters if you're overclocking as far as the chip can go.
I'd probably go with ivy bridge now, just because an i5-3570k is more than enough to handle anything for a long while.
(Also, oddlyinsane, I'm thinking you meant to say that power efficiency and a better igpu
aren't really essential for desktops?
)