Many studies explored the effectiveness of augmented, virtual, and mixed reality for object placement tasks. Two main approaches for assisting users during object alignment exist: static visualization techniques and interactive guides. This paper presents a comparative evaluation of four static visualization techniques used to render virtual objects when precise alignment in 6 degrees of freedom (DoF) is required. The selection of these techniques is based on the amount of occlusion caused by the visual guides during the alignment task. To the best of our knowledge, no previous work exists that evaluates which visualization technique is most suitable to support users while precisely aligning objects in virtual environments. We designed a virtual reality scenario considering two conditions -with and without time constraints- in which users aligned pairs of objects. To evaluate the users performance, quantitative and qualitative scores were collected. Our results suggest that visualization techniques with low levels of occlusion can improve alignment performance and increase user acceptance.