Karl Malone was the best at taking advantage of the rules during the years he played. He would have a much harder time succeeding with today's rules unless he extended his range.

However, if the criteria was: Who is the best PF at succeeding with the rules they had in place, I think Malone is the guy. If it is: Who would be the best PF under today's rules, it would probably be Dirk (assuming his prime years). If it was: Who would be the best power forward under all the rules (average if all played a season using each of the different set of rules), it would probably be Tim Duncan.