Historically, the CM (Chaos Map) has become the foundation, and it's through it that players learn to play other map types. It's also much easier for true beginners to start learning map strategies with just one map. I can't come up with one specific map for these tasks. Although, perhaps this is already a relic of the past, as the participants in this tournament have already played on all the maps before the tournament.
Personally, I would be against Jebus, but for some reason, the overwhelming majority seem to like it...