A personal, upbeat tone.
Rhetorical devices are techniques that an author or a speaker uses in an attempt to persuade the other part about something. It is also used to evoke emotions.
There are many techniques to achieve specifics effects like hyperbole, alliteration, metaphor, etc. Some of these devices could be considered as figurative-language because they depend on a non-literal use of the word.
Because of this, I believe that the best option is a personal, upbeat tone. By using an upbeat tone you are trying to evoke a positive emotion on the crowd. And with the personal tone you will be able to use the figurative language better than with a professional, factual tone.
