Looks don't matter mate
Performance should always come first! The mobo will be in the cabinet anyway!
As for OC, the Asus is a beast. That board is MIND-Blowing. I never really liked the Extreme6. Okay it's good - Nice features and all, but afaik it's not better than the Asus P8Z88-V or the Gigabyte Z77X-UD5H..
The Asus has an AMAZING UEFI Bios and comes with amazing softwares for real-time hardware handling and management. I highly recommend you get the asus. The board has great reviews too!
ASRock is an amazing company too btw. Just the Extreme6 isn't THAT good. ASRock is good for X79 boards and the Extreme4 - Probably the most commonly used Z77 board.
So, make a choice between the V-PRO or the Gigabyte Z77X-UD5H.
Ps: Go for the Asus
Trust me, you won't be disappointed!