All 3 are perhaps 3 of the 4 largest manufacturers, the 4th being Foxconn. All 3 will have similar deadlines for pushing out BIOS updates especially for supporting unreleased CPUs etc as they get that information from Intel long beforehand. Perhaps the question you need to ask is which company has less of a need to issue updates because their board is already reliable and stable? Unfortunately that's quite subjective aswell and people will vary their comments depending on who they've had experience with.
My subjective opinion is this: I have had mobo's from those 3 over many years and I have had many positive experiences with MSI, 1 negative experience with Asus (not due to their hardware but their in built windows BIOS flasher, won;t be using that again) and my first Gigabyte board is the one I'm using now. Overall I am very pleased with my Gigabyte board as it has 'just worked' with everything I've thrown at it- including 4ghz OC. Therefore I'd suggest Gigabyte and MSI for their motherboards and especially for Core i5/i7's I'd suggest Gigabyte.