Depends on how much you want to spend.
If price is not a consideration
1. Asus RoG Maximus VI Impact
2. Asrock Z87E ITX
3. Asus Z87I-Deluxe
The Maximus VI Impact will be pricey. Likely between $250 to $300 USD. Where as the Asrock Z87E-ITX and Asus Z87I-Deluxe will be around $150-$175.
The Maxmimus VI Impact is by far the best, but are the additional features worth the added cost you?
Personally I'll be buying the Maximus VI Impact. Hopefully NGFF SSDs start hitting retail channels soon. However If I had to choose between the two next best itx boards, I'd take the Asrock Z87E-ITX over the Asus Z87I-Deluxe because it for sure has msata, and possibly better audio, and will likely be cheaper.
What you buy also depends on when you want to buy. Right now the only Z87 itx board thats attainable is the Asrock. The Asus Z87I-Deluxe should be hitting retail channels any day. Where as the Maximus VI Impact will not be hitting retail until sometime in July.
Edited by wreckem - 6/4/13 at 1:23pm