The GA-Z68X-UD3H-B3 is the "better" board, but it all depends on what you want to do with it. You always want to go with the "UD" boards, though.
In any case, what CPU do you want to use with either one? If it's an Ivy CPU, you pretty much have to go with the Z77 board, but if it's a Sandy CPU you can go with either board.
Also, the Z68 UD3H is SLI capable and the Z77 D3H isn't, among other things. The UD3H boards just have a lot more features than the D3H boards and are generally better for overclocking. The UD5H boards are even better.