No strong preferences - I'll watch any. I've voted for UV Pacifist, since they often seem completely miraculous (the next compet-n update will include some incredible ones), though NM has that tendency too.
Probably my favourite single-map demo of all is Cameron Prosser's TAS NM Pacifist on HR map22.
Coop demos can be fun too - a good example would be Anders and Henning's 30NM coop.