May the odds be ever in your favour~
It's really pretty much luck anytime during the warranty period.
As for Asus or MSI, you should compare features and aesthetics and read up on it's real-world usage (i.e. our own royfrosty's review on the recent MSI mobo.) in various forums around the web.
An informed decision is miles better than simple hearsay.
However, I can understand how we as humans get 'burnt' when we encounter nasty incidents when dealing whichever brands (RMA, product itself, etc). This would ultimately makes us extremely bias or learnt something out of it. But thinking about it, it's really just bad luck at play.
Unless of course the product batch has serious QC issues, then that's another story.