Here's my Thoughts.
ASUS - If it works, and u never need to RMA, and its NEW in BOX... its still a good gamble. (only you will be supporting them)
GIGABYTE - Components look and sound expensive, but in actuality its MEH~. RMA is close to ASUS.. they don't destory your RMA, but they will lose it for a while, or send you back a refurb in worse physical then the board you sent in, but working.
MSI - Sigh... i don't have enough to go on MSI honestly... they were not known for quality until about 2009 when reps started coming out to overclocking meetings and started asking people for help. This is when you saw the "military grade" gear, because we told the rep straight out, your components are dookie, and i think he told the boss that. Next thing we see is the "military grade" stuff coming out.
Someone else like
@Markfw who has a LOT of MSI stuff can probably speak more.
eVGA - RIP... BEST of the BEST... You'll be missed....
ASRock - These guys have been my goto lately. I heavily push the TaiChi. I even am responsible for pushing it on Mark even. The TaiChi is a UGLY board, but its the rock of Gibraltar for most of my builds i have done with it. Its SUPER stable, SUPER durable. I can't say more besides it being really UGLY, and also missing some of the more luxury features the higher end boards have on other vendors.