Cochlear implantation (CI) for the treatment of single-sided deafness (SSD) is a relatively new treatment modality. Although comparing the effectiveness of CI and contralateral routing of signal (CROS) hearing aids (HAs) is important, very few reports on this topic exist. In this study, objective assessments and subjective assessments were conducted to determine which SSD individuals would prefer CI or CROS HAs. Objective assessments (speech perception and sound localization) and subjective assessments (Hearing Handicap Inventory for Adults (HHIA), Abbreviated Profile of Hearing Aid Benefit (APHAB), MOS Short-Form 36-Item Health Survey version 2 (SF-36v2)) were performed on 87 SSD patients. Of the 87 SSD patients, 33 patients hoped for CROS HAs, and 17 patients hoped for CI. The CI group underwent subjective and objective assessments at 6 and 12 months postoperatively. The CROS HAs group underwent objective assessments at 1 month after wearing CROS HAs. After the intervention, the localization ability was significantly improved in the CI group (p < 0.05) with no significant improvement in that of the CROS HAs group (p = 0.48). No significant improvement in speech perception in noise was observed in the CROS (Signal-to-Noise ratio + 10, p = 0.08; SN + 0, p = 0.17); however, a significant improvement in the CI group was observed at 12 months postoperatively. The APHAB subscale "background noise" and SF-36v2 health concepts of role-physical, general health, vitality, role-emotional, and mental health were significantly higher in the CI group. CI was superior to CROS HAs in speech perception in terms of noise and sound localization. Patients with postlingual acute-onset hearing loss and more handicaps and a more positive view of their hearing loss possibly tend to choose CI.