Background/Objectives: Implant-based breast reconstruction (IBBR) is increasingly favored over autologous reconstruction due to its procedural simplicity and recovery benefits. Conducting this reconstruction using either the subpectoral or prepectoral planes has varied aesthetic outcomes. This study utilizes VECTRA XT 3D imaging to objectively assess breast symmetry differences between these surgical techniques. Methods: A retrospective cohort study was conducted analyzing data from patients undergoing unilateral total mastectomy followed by immediate silicone implant reconstruction via subpectoral or prepectoral techniques. The VECTRA XT 3D system provided measurements, including sternal-notch-to-nipple (SN-N), midline-to-nipple (ML-N), and nipple-to-inframammary fold (N-IMF) distances, as well as breast width, volume, and projection, taken more than a year postoperatively, to assess symmetry and aesthetic outcomes. Results: The study included 63 patients—29 in the subpectoral group and 38 in the prepectoral group. The SN-N ratio was 0.91 for the subpectoral group compared to 0.95 for the prepectoral group (p = 0.014). Among patients with a BMI of 25 or higher, the prepectoral group had an SN-N ratio significantly closer to 1 (0.97 ± 0.07) than the subpectoral group (0.89 ± 0.06) (p = 0.027). No statistically significant differences were found in metrics based on the surgical method across age categories divided at 50. Conclusions: The prepectoral IBBR technique shows improved nipple positioning and breast symmetry compared to subpectoral methods, as assessed via precise 3D imaging. This finding suggests potential advantages for surgical planning and patient satisfaction, indicating the need for large cohort studies to further investigate the factors influencing breast symmetry.