Answer: A voice that is critical of Darcy
Step-by-step explanation:
In this passage, the narrator is comparing Bingley's and Darcy's personalities in regards to their relationship. Bingley is described as loved by [endeared to] Darcy due to his easy-going, peaceful nature, whereas Darcy is stated to be almost the complete opposite, offering a 'greater contrast'. Therefore, it can be assumed that one would describe Darcy as quick-tempered and less peaceful that Bingley.
Although the tone of this passage could be classified as analytical, the stark contrast that allows Darcy's character to be judged makes this voice more critical that analytical.