I honestly believe both games are equal in their own way, but apparently the community feels different.
The only shocker that made me scratch my head in confusion was the fact that Morrowind had better addons. Then I remembered that Bloodmoon and Tribunal count as addons.
Morrowinds modding community isn't exactly as expansive as Oblivions modding community these days, but its the advancement in things like quality and content that make it better than Oblivion. Take the morrowind graphics extender. This graphics accelerator puts the game at the same level (if not higher) than Modern MMO's.
Oblivions story was quite boring, as you were simply a piece of something bigger than yourself. In Morrowind you were
that something. Shivering Isles fixed this issue for Oblivion players, but sadly not in the original game.
Oblivion has great combat mechanics, graphics and a streamlined questing system which makes it far superior over Morrowinds. I feel like the nerevarine walked around with a mini cassette recorder, capturing everyones dialogue word for word.