i don't like the lack of PCIe x1 slots on the MSI, because i think that PCIe expansion cards are really going to take off (sound cards, DVR cards, etc). MSI is doing this on a lot of their boards, like their ATI chipset, and i think it's one of the last things they should have cut, rather than the first. I've heard a lot of bad stuff about MSI, but never have used one myself. However, i have no idea how it performs, so i guess we'll have to see some benchmarks.
I had an A8N-SLI, but the SATA-II controller died, so i returned it and i'm now about to receive a chaintech NF4 ultra. I liked the layout of the board, the performance and stability, and all the extras it came with, but i did not like the rather confusing bios with seemingly missing things (there are like 5 different obscure things related to overclocking, like AI N.O.S, PEG LINK, etc, none of which are explained in any clear detail). Also, even though there is supposed to be a PCI lock, there is no setting for it, and when i open ntune, it warns me that the PCI bus is tied to the FSB and i need to disable it, and i have yet to see an option for the SATA-II controller regarding NCQ, which my Diamondmax 10 has. And of course, my mobo stopped recognizing my HDD, so i had to send it back, and i had a hell of a time contacting tech support (they only have a local number rather than toll free, so i had to use my cell phone, and the wait to talk to a representative was like 20 minutes, after which i was told i'd get a call back "really soon" which never happened. What a pain. Finally i just called the reseller and sent it back to them.)
Honestly, based on board reviews i've seen, the Gigabyte K8NXP-SLI is gonna be the board to beat, as it has all the features of the Asus board, but i like the layout better and the performance and overclocking results are absolutely amazing, running like 5% faster than stock NF4 boards, which were just as fast as all previous nforce and VIA chipsets. The FSB goes to like 350MHz i think, as well (Asus goes to 400, but who makes DDR800, lol). Unfortunately, i've only seen it for sale like once, and since then it's nowhere to be found. Still, if you can wait a few weeks, look out for this board.