I don't even think you really need to compare Game of the Year to Oblivion. Tribunal disappointed me for being locked in the capital city (okay, plus the underground),and then I find THIS is really Morrowind, and what I thought was Morrowind was just the Vvardenfell province, although I dug the flaming sword you eventually get: I used that as a torch the rest of the game. Bloodmoon was nice in that it was another land to explore, albeit smaller, but even having trekked across the entire island, I still found it difficult to find places and things.
As for the actual core game, yes, Morrowind is far superior to Oblivion. In Oblivion, I am (currently) the Arch Mage, the Gray Fox, the Listener, a Master Fighter, Grand Champion, Divine Crusader, Lord Sheogorath, and I haven't even started the main mission yet! Why is it so easy to head up everything? Why don't some of these conflict with each other. A Divine Crusader who also happens to the head the local murder for hire guild? In Morrowind, heading up both the Fighters Guild and the Thieves Guild is damn near impossible. That I like, it's more realistic.
I also like Morrowind's magic better. More spells, varied spells, and damn near anything can be enchanted with any spell you choose. I spent almost 24,000 gold on a permanent 4 point health regeneration amulet, and it was worth every penny. Oblivion, you can't do that. Also, Morrowind's enchanted items recharge themselves over time: Oblivion's require intervention, with the exception of Dawnfang/Duskfang (the last sword you'll ever use), but hardly makes up for everything else.
Morrowind also has the superior weapons and armor repair. Anyone with a hammer can repair any item, anchanted or not. Oblivion's requirement of skill before repair of enchanted items can commence is utter bullshit.
Not that Morrowind is without fault. Even with silt striders and boats, it can take far too long to get anywhere, assuming you can even manage to find the place. Of course, fast travel is the polar opposite: too easy. A middle range would be nice for the inevitable Elder Scrolls V. Silt Striders, boats, and your horse would be more idyllic. Besides, my armored Shadowmere came in handy a great times in battle.
Also, the combat. Even later in the game, hit detection was awkward at best. I also hate the Cliff Racers with a passion. You don't usually see them until they're on top of you, hitting them is a bigger ***** than everything else, and at times they travel in packs of five or six! I'll still take that over ogres and minotaurs who simply ignore my shield and bludgeon me to death, though.
But back to ragging on Oblivion. Morrowind allows you to make choices which may affect the future. Hell, choosing you gender at the very beginning can have it's effects. Trust me when I say join House Hlallu as a female. Any dealing with Crassius Curio thereafter are hilariously misogynistic. Oblivion, nothing ever seems to have massive waves like that, although Shivering Isles is closer.
The world: Morrowind is far more varied, Oblivion is far nicer to look at. Shivering Isles adds more variation, and for that, I like it, aside from the sweet sword and the whole god of my own dimension thing. Plus TWO personal armies at my disposal!
I didn't realize I had that much to say about this, so I'll attempt to wrap this up before Elder Scrolls VII comes out for Xbox 1080. Neither has flaws so glaring I'd banish one or the other from my PC. I wouldn't exactly call one the best game of all time either, but they both have their good points, and if they are combined when the next one comes out (I just assume another is on the way), that one may a serious shot at the title.