They all sound fine. You've picked the 2 best companies for Intel overclocking. I used to use Abit but they have long since dropped from the top. We're talking 2000 when overclocking PIII's and UDMA 66 was an upgrade many considered worthless because of the slow hard drive performance. Oh yeah, and when SLI was a 3DX solution that utilized 2 PCI slots... the good old days. That's when Abit was king, but ASUS has taken that position with Gigabyte right on their heals.
If you had to choose, look for features that you will use other than overclocking. I personally went with a P5B-E for my e6300 overclock. I didn't buy into the deluxe version like 90% of my peers. I didn't NEED nor in many cases want the extra features offered (wifi and an extra gigabit ether). For me, it was price that came into play. I tried an MSI board, was horrified with the overclocking and constant bsd's after installing their bundled software that I got this ASUS. Never looked back.
Oh yeah, and I did NOT need SLI or crossfire support. I don't believe in SLI from an environmental stand point and the fact that I don't run high enough resolutions to warrant said expense.
Having said all that, just get what you need, everything else is a waste. I hear so many people talk about upgrading blah blah and "down the road I want"... guess what, it never happens. Life happens, build a system and if you're a gamer, plan on upgrading your graphics card ONCE on the lifetime of your mobo/cpu combo. Don't bother upgrading your CPU in the future (you're choice is at the top end of 775 socket).
This is coming from somebody that's been mentioned on another "Hard" ocp main site for helping be the 1st to overclock a celeron above 1GHz. I've been around for a while and nothing is future proof, not even these overkill (aka useless) 1000 watt psu's. Hello people, power requirements are decreasing, not increasing (green movement), and the connector standards are always changing!