Basically the amount you'd expect: if medical technology allowed me to regrow the finger with full use of it, that would mitigate it considerably. With current technology, it gets me a lifetime of inconvenience.

At the level of loss of a fingernail, I think the answer is a no-brainer: (a) gets me considerably less total pain, with both options protracted over a period of time that makes time preference mostly inconsequential (24 hours, and maybe a couple weeks); getting a fingernail ripped off isn't a bad enough experience to have any significant long-term impact on my mental state.