I can't think of this question without picturing most Mayweather fights... That is will vs skill.... Floyd makes other fighters will look completely useless...

So straight down the line I would have to say that having skill is more valuable over the long haul...
I have also seen plenty of bouts though where will has carried boxers through to some of the greatest wins in boxing... So it a trait that I always want in a champion... And boxing certainly wouldn't be what it is without the endless fighters that have unbeleivable strong will's to get through 12 gruelling rounds and still be putting in the same effort as round 1.