I'd definitely go Asus, better QC and just better quality, their CU models always seem to OC well, I'll be picking up the the 980, currently have the Asus 780 CUs (SLI) in my Z87 Hero and their 290X Matrix in my Z97 Hero
I would say an Asus model as they generally have better QC and customer service than MSI (some people will disagree with me, of course). Go for the 970 as it's WAY better than the 290.
Well, MSI's motherboard QC is crap, and you wouldn't want to take chances, do you? I would personally go with Asus, but you might want to wait a while for the DirectCU II model to come out as the reference design (what you have right now) doesn't cool very well, with 1 fan and all.
I'd definitely go Asus, better QC and just better quality, their CU models always seem to OC well, I'll be picking up the the 980, currently have the Asus 780 CUs (SLI) in my Z87 Hero and their 290X Matrix in my Z97 Hero