Personally I find active voice to be more repetitive as it tends toward a similar sentence structure of subject-verb and can also imply certainty in situations that are more nuanced. However, active voice and simple sentence structure should be used when possible to avoid redundant, flowery language.
1. It lets you know who/what is performing the action, instead of leaving it to the reader to figure it out.
2. It makes the writing less repetitive because each descriptive word becomes a verb, instead of "to be" being in every sentence.