Under $200: MSI GD70
In truth, there are not that many options for high-end AM3 boards. I'd wager this is because AMD customers tend to be looking for both value and performance, but this is only my opinion. Whatever the case, the MSI GD70's price of $170 dollars makes it cheaper than any X58 board that you can currently buy. And that's impressive, because the MSI GD70 is one hell of a motherboard.
The basic features of the MSI GD70 trump both the Gigabyte and ASUS boards. If you thought that the Gigabyte's 6 SATA ports was a lot, well, take a look at the MSI GD70. It has 8 SATA connections. It also supports memory all the way up to the DDR3 2133 when overclocked, although you'll have trouble getting a hold of DDR3 2133 without selling your soul. Notably, the MSI GD70 does lack Firewire, but it gains eSATA. The MSI board also offers more RAID configurations than either of the previous motherboards.
Past that, things go a bit nuts. The MSI GD70 offers a total of four PCI-Express slots which, with four cards installed, arrange to run a x8 on every PCI-E slot. This also means that, with only two cards installed, both will be running at x16. You'd have to spend over $200 dollars to get that on most motherboards, but the MSI offers it here for well under $200. And don't think that MSI as skimped on the BIOS, either. Although it isn't notably better than the one on the ASUS M4A78T-E, that is no knock against it. The MSI's most insane feature is its plethora of buttons, including an overclocking dial which allows the user to overclock the processor by increments set in the BIOS. This is less useful than it sounds, but it can be nice to have when benchmarking an open system. In any case, if you're looking to build an extreme gaming computer, the MSI GD70 is the best bet.