I'm a big fan of ASRock personally. You get fantastic features for the price and I've bought quite a lot of their boards now (must be over 6 by now) and have never had any issues. I know others have had different experiences and 6 boards is hardly sufficient to draw global comparisons, but personally they're my go-to brand because of what you get for the money.
The Killer stuff, on the other hand, I would pay money to avoid. It's all a bit of con that a NIC can reduce ping times... as if how you prioritise traffic on your gigabit local network and maybe ~50ft of cable can make a difference to the hundreds (thousands?) of miles of cable running at much lower bandwidths between your property and the servers you're talking to. Plus, I've seen heaps of forum posts with issues with Killer networking stuff.
The upper-mid range motherboard of choice for me at the moment is the ASRock Extreme 6. It's got an Intel NIC (and a second Realtec NIC) which I'd PAY money to take over a Killer solution, AND it's got the PCIE 3.0 x4 M.2 slot, which makes crazy high speed storage an option in future. That'd be my pick personally.
The Gigabyte is good motherboard too though.