H.264 offers superior compression/quality ratio compared to basically every other video codec out there, including DivX/XviD. This is a fact.
Matroska and MP4 are both container formats that support H.264 video natively. AVI does not. Matroska also has incredibly good softsub support and allows you to use even wider variety of formats than MP4. These are also facts.
AAC also offers superior compression/quality when compared to MP3. There's also Vorbis, which offers somewhat better quality than MP3, but it also completely free and open format. These are facts too.
AVI and XviD are inferior formats. This is the ultimate fact.
My perfect anime encode would be H.264+AAC video with ASS subtitles inside MKV.