Flashy: Your message or platform is emotive or highly sensory for any one of thousands of reasons. A big one being your audience. Or, if informational, you play to a subversive position.

Simple: Your message or platform is aligned with themes that are generally economical, efficient, informational. Or, if emotive, they intentionally play to an underdog position.

I'd generally be careful about asking people from a simple place whether simple or flashy is best, so it's an interesting post :-)