it's up to you, if you are going to sli or crossfire then get ASRock as it has support for both sli and crossfire. Looking at Asus board, it does have support crossfire support but doesn't support sli. Get the cheaper one if you are just going to stay with single gpu become there won't be any much difference with overclocking as overclocking abilities for both will be identical.
the asus z-87 plus has 4x SLI and CF support and is th same price as the asrock.
generally i would say asus is considered a better brand than asrock is.
i've used both asrock extreme boards and asus boards and i prefer asus myself. i've had the silly asrock super flash speed program drivers kill flash drives on me, the bios was a bit harder for me to navigate since they have things named oddly at times but all of my issues were relatively minor.
your choice but i'd personally say something from asus would be my first choice.