I am looking for the best rendering format for ease of use. In other words, which format to render in that will play on other computers without issues of codecs, incompatibility, etc. Of course, I would like the format to also have fairly good quality/compression.

Which format crosses computers (assuming windows os of course) the best?

Thanks in advance.

P.S. I want this to play without needing to download a codec if at all possible. Many of the people trying to play it will be behind a firewall that often makes downloading codecs impossible.