If you mean Devyn as in the first 2.8 years of his collegiate career, the answer is Roy. If you mean 2013 NIT Devyn, the answer is Devyn. It's NIT Devyn against damn near anyone. PG, scoring, rebounding, defense. He has put on an absolute clinic this tournament.
Yet, as someone who was at Iowa when Roy was, he was the better of the two to date. Every year the father was better at that year of his career than his son. It isn't even close until this year, even though Devyn was pretty good last year. That isn't a slam against Devyn, either.
Devyn is close in the last four games. Maybe as good. Will Devyn be better as a senior than his dad? I guess we will see.