Well let's compare the two, hm?
Story: In both games, cliche and mediocre. So they're evenly matched there.
Side quests: Yes, Oblivion's were better by a small margin, the side-quests in Skyrim were far too predictable and boring, though there were a few gems. (Sanguine Rose quest, restoring the thieves guild)
Freeroam-ability: Better in Skyrim because of the fixes to leveled enemies. No more bandits with Ebony armor as soon as you leave the starting area!
Other gameplay functions: Skyrim all the way, Bethesda seamlessly added new things (dual wield) while getting rid of old, useless, or annoying ones. (Weapon repairing, mortar and pestle, birthsigns)
Music: Meh for both
Graphics (least important to me, personally): Skyrim.
Looks like Skyrim wins, boys and girls!