We all have our preferences and there's no denying the performance of a X79 based rig. However, if you do a forum search for GAX79-UD3 and Z87-UDH4 side by side... one hit for Z87... 2 pages of hits for the X79... more popular, maybe, but also problems.
I'm not interested in getting into a discussion about reliability and performance, or what's better. However, one of the things I always do before buying a board is look at its manufacturer forums for people having issues. People don't usually post how great there board is. They are often here looking for solutions to problems, and/or to help others. All comes down to price point really.
