We go with MPEGs for the simple reason of less hassles. When doing almost any other format, there's a 99% chance the surfer will need to download and install some type of sofware or codec to play it back. To many people in here, that probably seems like a simple enough task but, apparently, with Joe Public this causes major stumbling blocks (at least it did a few years ago).
Offering both MPEG and a higher resolution version in a superior format is a possibility for keeping everyone happy. The only downside to this method is the extra server space consumed (and making the 2nd set of compressions).
Hmmm... maybe the members in that poll prefer MPEGs so they can take'em over to P2P networks and trade'em with their buddies.
