Both AOSS and SES can automatically configure a secure wireless connection with the touch of two buttons. User interaction is similar and, while both user interfaces could use some tweaking, simple enough for first-time wireless users to successfully execute.
The main difference between the two is in installed base and commitment to the technology. Buffalo has the edge here with (they say) 6.5 million AOSS current users, availability across all its current consumer wireless LAN product line and ongoing recruitement of new companies to AOSS-enable their wireless products.
SES, by contrast, has virtually no installed base, is still not released by either Linksys or HP six months after being announced at this year's CES, and is MIA on both Linksys and HP's websites. But given the marketing and distribution muscle of both companies, SES could easily overtake AOSS should both companies decide to get firmly behind the technology.
What's really needed is for these two separated-at-birth technologies to merge into one, preferably under the umbrella of a Wi-Fi Alliance working group similar to the one that resulted in WPA. This might not get wireless security that the "average Joe" could set up into her hands any sooner (given the glacial rate of rollout of WPA and now WPA2 by WLAN product manufacturers). But it would certainly serve "Joe" much better than the current battle between two technologies that are more alike than different.