Deadest World?

For a somewhat better measure of activity than the mere number of over 120's (who could be mostly abandoned), I recommend the Southperry ETL. Sort by descending exp/day.

You can see that, for example, in your homeworld of Broa, the 100th most diligent character in training is getting 269m exp/day.
In Galicia, the 100th hardest grinder is making 123m exp a day. In Kradia, it's 80m. In Yellonde, 40m.
You can also see in these lists how bot-infested a world is...

I also recommend making a visit to FM in each world.

Thanks for the tip, I'll do that. I mainly plan on completing the game as best I can on my DS.
as in all monster cards/familiars/quests. << Massive timesink + accomplishments a hacker cannot take away.