The 2013 edition of QuakeCon, the long running BYOC (bring your own computer) gaming event, is happening right this second. And the keynote was again delivered by John Carmack, who in addition to co-founding id Software, is one of the most respected game developers you'll find working today.
Carmack is credited for helping to shape the PC gaming spectrum, not just via on software front, via the games his studio makes, but on the hardware end as well. The technological boundaries that he constantly pushes often sets the pace for PC game graphics across the board.
This is why, every time a new console is released, which are the PC's director competitors, everyone's always eager to hear what he has to say. And both the PS4 and the Xbox One did come up in his speech.
Carmack mostly touches upon which he thinks is the best, since he's all about seeing which machine is most powerful. Simply fast-forward to the 24:48 mark in the following video:
Basically, they're both very close, and more importantly, "they're both very good". He also notes how, in the past, we more of a fan of the 360; the fact that its architecture was so close to a PC, far closer than any previous console before it, definitely helped.
Sony has made a big deal that they new system will be developer friendly, and as it turns out, this is very much true. Though Carmack also states that he's not yet sold on the Kinect, which is unfortunate for Microsoft, given that it's such a major pillar of the One.
While conceding to the fact that it might not be for the kind of developer that Carmack personally is, he still takes issue with the tech, specifically the its latency and interactivity, or lack thereof. Carmack compares it to the universally reviled one button mouse that Apple used to produce.
Basically, don't expect "Doom 4: Kinect Edition" for the Xbox One anytime soon.