The GB bios improved ever since they changed BIOS maker company whatnot. Still, people seem to have bad luck with the current X79 line-up of GB so I'd stay away. For X58 I remember them being up there with the best, but since then I've lost a lot of faith in them.
IMO GigaByte, Intel, ECS and MSI are brands to stay away from.
I'm curious about how well AsRock is doing though
Sadly, I have to agree. The Gigabyte p45 board was the last Intel socket I owned before getting an x79-ud5. While there were some issues with the ep45-ud3r, it was always a solid performer. The x79-ud5 has caused more problems than I would like to admit.
Initially the UEFI allowed "damaging overclocks," or at least that's the PR reason Gigabyte gave when people started burning out their crappy VRM... The F8 UEFI did much to make sure that VRM could not be burnt out, but it also took a substantial amount of the finer tweaking options away. On top of this, the UEFI remains relatively unstable at the current F10 revision. I am getting occasional hardware faults, even without pushing the multiplier past 38 (125 Mhz clock with 100 base and 1.25 multiplier); Gigabyte's own PR has suggested that most SB-E processors are capable of that easily...
Truthfully, I would skip Gigabyte for x79. They aren't getting a good reputation, and it isn't undeserved. I haven't had an AsRock x79 board, but I've been able to play with someone elses. The x-ram is pretty much a joke, but the other features are very nice. They've got a decent, if different UEFI. The overclocking seemed very comparable to Asus, which is the best selling x79 brand for a very good reason. ~sigh~
Don't waste money on Gigabyte for x79. They really screwed up, and have yet to even acknowledge their error. I wish this wasn't the case...