TBH I'd kind of discounted the MSI as I've never had one of their motherboards and am thus a bit wary.
For me it's really between the Asus and the Gigabyte. The Asus seems better featured but I've seen quite a few reports of problems with it, probably due to the new EFI BIOS. I've got five machines here with Gigabyte motherboards and I trust them so I think I might just go with the UD4 for "safety".
I've sold my current CPU and memory today but can steal the Q9550 and memory out of my second machine to tide me over so I may wait a little bit for more info, tests and BIOS updates to appear.