Like DJDeCiBel said both are good boards but the UD3H has some extra features for $15 more. They're pretty much the same board overall, but you get some extra switches installed on the UD3H board that you dont with the D3H. Like power button, reset, bios switch, theres a display port for the intel graphics (if you use an IB chip), 6 plugs for audio (5 on the D3H). The UD3H is better if you want to OC, as it has more features for doing that over the cheaper board.
I prefer to use Gigabyte boards since in my experience they have given me the fewest headaches when building a system. And I like the Dual Bios feature which both of these board support. Either way pick the one that fits your budget and your needs. They should both give you a few years of good use.