This is completely inaccurate. Most users cannot tell the difference between onboard sound and a separate sound card. Any decent sound card costs a lot of extra money and is only useful for priority features like having a separate headphone jack to make use of audiophile headphones. Onboard audio has made leaps and bounds, especially Realtek ALC1150. It will be as good as just about any separate consumer sound card out there. This is 2013, not 2006. Separate sound cards are mostly useless (aside for professional work, or being a sound aficionado). Current onboard offerings are more than good enough.
I would go with the ASRock Extreme4, OP. Definitely better price to performance than anything MSI offers in the same price range.