There are ways to measure cutaneous sensitivity in various parts of the body objectively.

Here is the conclusion from the study: The studies uniformly found that circumcision had no overall adverse effect on penile sensitivity, sexual arousal, sexual sensation, erectile function, premature ejaculation, ejaculatory latency, orgasm difficulties, sexual satisfaction, pleasure, or pain during penetration.

Paper: Does male circumcision affect sexual function, sensitivity, or satisfaction?--a systematic review by Morris and Krieger in Journal of Sexual Medicine in 2013.

You can read about their methodology and the papers they covered in there if you really want to find out the quantitative measures they used.