Yes, the ASRock Extreme 4 has been a solid line. 4670k might be about the same price as the 3570k but what about comparing Z87 vs Z77 mobo prices? Usually Z87 is more expensive.
If mobo price difference is only $10, then I'd get the Z87. In the real world, you would never notice the difference between the 3570k n 4670k.
You won't make a wrong decision with either choice.