My vote goes to the RII GENE, although I have not used other mATX X58 boards. I can tell you about the RIIG,
PROS: very solid board, looks great, overclocks great, performance is very satisfying, tons of bios options for tweaking, Asus does offer advanced replacement on this board, SLI and Crossfire support, SupremeFX X-Fi built-in (although software emulated still great for those non audiophiles), price, support for upcoming Westmere (last 2 bios updates was for new CPU support) and I'm sure there's a couple of things I forgot to mention as well.
Cons: NB runs HOT actually needed to add a small 40mm fan to help keep temps decent, lcd poster (to me at least, kinda pointless) I think that's really it for cons, as you can see the pros heavily out weigh the cons on this board.