Tbh, I'm personally not biased towards any - despite pretty much only recommending MSI boards on here.
The Asus line of P8Z77 boards, along with the Maximus and Sabretooth lines are just as good as MSI boards. Same performance, and possibly more features (although a lot of those are things you'd never actually use).
But, MSI were able to price their ranges a lot more competitively. Where Asus give you a lot more features between the LX, Pro and Deluxe boards, the price differences between them are significantly more - was about £50 between them when they first came out. The MSI boards had only £10 or so between the GD55 and 65, and only £20 iirc between the G45 and GD55... However, MSI didn't really offer much performance, or feature differentiation between their lines.
I think it all comes down to price. If the P8Z77 deluxe could be offered for GD65/mPower price, then I'd probably recommend that. They're both amazing boards, and all the ones I've mentioned here can easily reach maximum safe 24/7 overclocks on Ivy of around 4.5ghz depending on the chip of course.
I just think performance wise, Ivybridge took a lot away from the motherboard - the memory controller for instance and so less is required from the motherboard in order to get decent overclocks. If that's the same for Haswell - which I think we can all assume it will be, then I don't think there will really be much point in anyone spending over GD45/55 pricing in order to get great performance and features.