The MSI armor is actually a good choice. The fans are double ball bearing, so they should last a bit. You cant really overclock them that much, but I have a few that run at 0.89v easy. power consumption is really low (i have 470s). I made a review here: http://www.cryptominingtalk.com/msi-armor-470-4g-review/
You should check out the sapphire nitro fury on newegg, sometimes its a really good sale. Could be a worthwhile alternative to the 390 if you want to go that way (more hashing power per rig).
edit: the last rx470 msi armor 4g i got had samsung memory. all the others hynix.
Did you have much luck with the samsung card?
I just got my first armor card. had my fingers crossed for samsung.. which I got but, not too sure so far, 990mv just to get it to stop throwing hw errors at 2040mem 1750strap..
Have a feeling it's gonna drive me nuts like my first hynix card did

nm.. still slow errors, bah.