Ogg vorbis is much better position than theora. vorbis has accepable quality and some nice
features for web, such as peeling (dropping bitrate without recompressing), has seen patent
review and is in widespread use by community and industry players like samsung and software
houses wanting to avoid mp3 tax. The main disadvantage is that vorbis isn't really
dsp-friendly, which makes it hard to implement bugfree in low-powered portable players. This
is not a problem for the html5 video tag really.
Ogg theora on the other hand is technically inferior, and rarely used. Even the <a
href="http://www.effi.org/tapahtumat/bb-seminaari-07-videot.html">EFF finland site</a>
provides videos only in H.264 and mpeg2 format! I don't think the community is very honest
when demanding *theora* support from W3C when they are not ready it eat their own dogfood.
An interesting review would be the visual quality of H.261 (which is supposedly old enough
that all patents have expired) vs Ogg theora. With selected improvements, such as allowing
more video sizes, H.261 could become an acceptable baseline.