OK, just to add my two pennyworth to the debate:
QFlash is the safest way to update BIOS as it is done directly through the BIOS without the added layer of the OS which can cause issues when using @BIOS.
@BIOS is an acceptable way to update the BIOS but has been known, on rare occasions, to go wrong and cause the update to fail leaving users with a dead motherboard.
Some BIOS updates have to be made using @BIOS especially if the update is a larger file size than the BIOS already installed.
If you are using @BIOS it is safer to download the BIOS file, that you wish to update to, from the download page for your motherboard and use that, rather than use the automated method employed by @BIOS as sometimes, the latest version of BIOS isn't available to download from the Gigabyte servers.
Both methods carry some risk when updating BIOS and both are perfectly acceptable but remember the old caveat: "You don't need to update just because there is a newer version."
If everything is working OK with your system you really don't need to update the BIOS at all.