Well, best really comes down to what specific criteria you’re asking for.
Asus has excellent motherboards, which is good, as their support is–at least from what I’ve heard–nonexistant. My other gripe is their website. I hate their website, as do most people. Again, their boards are typically fantastic, but the support end is a killer.
While the memory pipe is nice, it’s going to really put a wrench in the works for any upgrading you’d like to do as far as RAM is concerned. Yeah, you can remove it, but from the looks of it, you’ll pretty much have to remove the motherboard to do that.
DFI is great, but due to the extensive BIOS options they tend to feature, I’d recommend against them for a newer builder. If you do your research and are willing to spend the time tweaking them, they are amazing boards. I love my NF4 Ultra-D, but I’d be hesistant recommending one to someone getting their feet wet in building their own.
ECS is fine. Typically a no-frills company, but for being a cheap brand, they work great.
Gigabyte is another good brand, and while they’ve not had a long history of enthusiast-class motherboards, they’ve had solid products.
MSI. Pretty good all around, and a safe bet. Typically, they’re not the killer overclocking boards, but I’ve used several of their boards without so much as a glitch. I would certainly recommend them.
I’ve heard good things about Biostar, and they look like the poor man’s DFI, but I have never used their products personally.
[strike]Abit[/strike] abit. I haven’t used anything of theirs in recent history, not since being renamed “abit”. They had a good reputation beforehand, but they’ve had a little trouble getting their stride since being purchased by USI a few years back.
I’ve played with a lot of brands throughout the years, and the only brand I’d avoid would be Epox. However, the company seems to have folded, so it’s more of a non-issue. PC Chips would be the only other company that I’d really steer clear of.