Both of the boards you are looking at are excellent, top of the line boards and you can't go wrong with either of them. I suppose how to decide depends on your needs.
The Asus board you are looking at has a few selling points: it has no chipset fan so it is very quiet. If you are one of those people who hate the sounds of fans chirping (and I am one of them) this is a nice bonus. I agree with Akifuddin on the point about not getting SLI. I happen to have the deluxe version of this board, and I have never used two cards at the same time, nor do I plan to. But that doesn't necessarily mean you need to avoid this board. Who ever uses ALL the capabilities of a board anyways? I have found the board to be extremely stable, and a great performer.
The Lanparty board too, another amazing motherboard that has won all kinds of awards for 939 sockets. The advantage of the DFI over Asus is its overclock-ability. Asus can't compare to the DFI board in this arena. The A8N-SLI is a very bad choice if you are planning on overclocking. Myself, I am not really into that game, so I went for Asus. I rarely have problems with their boards, and when I do, have found there tech support to be top notch.
Sidenote: both of the boards you are looking at are somewhat known to be picky about the ram you put in them. Be sure you research what ram will work very well before you buy.
Good luck!