Flavor is a tricky detail. The bride and groom need to be happy first and foremost. Next, the guests need to be considered. Basic flavors are an easy choice because they will satisfy most people (e.g. chocolate, vanilla, strawberry). If you want to be a little more adventurous, there are unconventional flavors such as creamsicle, pistachio & rose, and s’mores. You could also compromise by using more than one flavor in the cake or putting a unique flavor in the filling or frosting, which can be scraped off.