I don't have an effing clue, or care either (my biceps always outstrip my triceps, no matter what I do, it seems!
) but fwiw, I feel that the incline DB curl provides a great bicep workout.
Then there's a few lifters who do 100 rep sets of barbell curls. Seems to work for them.
Some say cables are the go, because there's constant tension, etc.
Haha, yeah, I dunno.