I have the z68 extreme7... it is my first asrock board and after using this for the last 7 months I would definitely get another.
I bought it because of features and layout for tri-sli.
There is more to it than just Read/Write numbers.
I do not own either of these drives but I would go with Samsung because of the controller they employ in the 830. (After reading up on the Samsung vs other drives... it will be the next one I purchase)
Here is a review of the Samsung 830...