I think it comes down to warranty now. Whoever offers the best warranty, gets your money.
Problem there. They are all the same. I can't speak for customer service because I have never had to use anyone.
Well, it really comes down to who you get. My experiences with ASUS have been great. I have yet to purchase a Gigabyte and ASRock board, so I cannot offer any insight on that. Gigabyte and ASRock boards have good reputations though, so I am willing to try them.
Nice choice on the NZXT Hale.
I probably would have chosen the modular Rosewill 450w Gold for a similar price though.