I've been an organizer of several hackathons and participated in Startup Weekend. The judging guidelines vary across organizers, theme, and city. In general,

I've been an organizer of several hackathons and participated in Startup Weekend. The judging guidelines vary across organizers, theme, and city. In general, Startup Weekend events focus on business model generation and customer validation, with building an actual product following. And remember, it's a weekend: the "winners" typically don't turn the project into an actual startup. I think of like in school, you can learn because you want to know things or you can learn to the test because you want the mark to move on. Would you rather build something hard or build something more likely to win? From my experience, it's not the same apps that do both. I also don't think one approach is necessarily better than the other, just personal preference, plus also depends on the team dynamic you end up with. For example, I wouldn't try to solve a hard tech problem on a team with mostly non-tech people because their expectations can be unrealistic. But if my team is 3 experienced startup engineers that can iterate, well why the hell not?