Which fighters have the most complete/widest skillsets?
There is a handful of boxers who do many, many things well and can incorporate defense with aggression.
(not gonna list prospects or guys who aren't already in the top 10 of their divisions)
My list of the most complete fighters in the sport:
Gennady Golovkin
Sergey Kovalev
Terrance Crawford
Roman Gonzalez
Manny Pacquiao
Vasyl Lomachenko
Takashi Uchyama
Kell Brook
Keith Thurman
Floyd Mayweather
Martin Murray
Rigo
Bernard Hopkins
There's a couple of them. Who else?
Did you not see uchiyamas last fight? The gentleman is showing his age.
I would recommend young Christopher Eubank jr. This fighter is a future pound for pound international superstar, and will be the one to beat Golovkin.