I'm in the human-centric camp. One of the things I liked about 3E was the way the race mechanics encouraged parties of mostly human characters with maybe a couple nonhumans thrown in for flavoring.
In the effort to spruce up the races, 4E has IMO left humans a little too far behind. The extra feat isn't as valuable as it used to be, the extra skill has always been more flavorful than useful, and the versatility of a third at-will power doesn't really make up for the loss of a second +2 stat bonus and the lack of a racial encounter ability. I don't see nearly enough human characters. As a matter of fact, thinking back, I've seen only a couple human characters in all the 4E games I've been in (not counting the one campaign where the DM enforced a humans-only rule). The campaign I'm playing in right now contains not a single human in a five-player group; we've got a tiefling, a half-orc, an orc, an elf, and a dragonborn.
I think humans ought to have two floating +2 stat bonuses instead of just one. Stat bonuses loom large in race picks; if you're looking at playing a Charisma rogue, for example, the +2 Dex/Cha options (halfling and drow) are very tempting, and it's tough to turn down that +2 to your secondary stat and the cool-ass halfling or drow racial powers in exchange for the mediocre benefits of being human.
If humans got two +2 stat bonuses, then they would become the ideal "fallback" race for any given concept. Continuing the Charisma-rogue example, halfling and drow would still be quite competitive options, but if you didn't like the flavor of those options, you could always fall back on human without feeling like you lost out mechanically. And humans would be the go-to race for any concept requiring an oddball combination of stats.