Seeing as it’s marked as Not Safe For Work, I assume you’re referring to which fingers you’d prefer to lose in a workplace accident due to not wearing proper gloves. In that case, I’d prefer to keep my index finger so I still have a grip with finesse.

This could be controversial, but…

if (target > (index + middle + ring)) { use(fist); }  
else if (target < (middle + ring)) { use(middle); }  
else if (target < (index + middle + ring)) { use(middle + ring); }  
else { use(index + middle + ring); }  

Of course, this doesn’t cover error handling, such as rejection.

Obviously I’d use my index and middle fingers on my computer mouse.

For what?