It is probably not cool to say so here, but to me, Morrowind is the Non Plus Ultra of all games of all ages. There never was nor will be anything like it. Why? Well...
Its world is gorgeous. One can fly. One may place one bottle upon another and continue to do so beyond where Icarus' wings melted, and after 15 years , that babylonian pillar still stands proud.
I have made structures from bottles, spore pods, weapons, shields, lights that are the size of a small town. Why? Because I came from Diablo 2, with its crap tiny inventory. I had to throw so many set items away that I was emotionally damaged, and then came Morrowind. The things my very first hero sold Irgola in Caldera are still there! No need to buy a ship.
And there is something else: Morrowind shipped with the Tool the developers used to create and populate that world : the TES Construction Set (CS). "Feel free to tweak whatever you desire." And so I did. After 3 years of vanilla, many of my Heroes were 50+, and even with difficulty maxed, there were no more challenges, no more real dangers. And when I started a new hero, he/she had to go to Vivec Telvanni to buy a very expensive Levitate and then to a Mage Guild to have them make a small one that I could cast with any chance fo success, go to Caldera for some Bound Weapons and tune those down, etc.
And so I added Teacher Foragers who sell tiny spells for the young one , and friendly fishes and dreugh, so that the level 1 in Seyda Neen could throw away their rags and swim the prison dirt from their body with hardly a chance to be attacked, while Baby Racers and Baby Netches gently float through the sky. And talk. And trade. Tiny things. Tiny budgets. Bigger comes later.
Why? Because I like it better that way, and Bethesda said : "Go ahead, the choice is yours. You don't have to mess with hexeditors and decompressors and whatever, here, use OUR Dev Tool !"
Skyrim may have Dragons, I have Nightmare Racers who spawn magic spitting Ash Racers, paralyzing Horror Racers even, when under attack, and who even may respawn after you kill them. You think that's it then? Nah. By the time you're 55+, there are way worse things in the sky. But even then there are the Baby Racers, and if you allow them, they give you wings. Modest ones at level 1, very fast at 60+
And that's only some of the Racers I added. Why? Because CS and Gimp and nifskope made it so effing easy to do so. And when I'm in a dungeon or another middle of nowhere and have looted so much that I can hardly walk anymore, or need some bolts or potions or whatever, I cast the appropriate Summon and trade, or travel. Why? Because I like it that way.
And if I'm in an area where there's hardly any action, I put on that funny hat, and prepare for more fun. And every once in a while, the hat adds a Tree Seed to my inv when it spawns a party, and wherever I drop such a Seed, a Tree will grow, and that Tree is hollow, so i can stow things in it that I don't want to sell and neither care to drag around all the time. And after I've accessed such a tree a couple of times, i notice the lights...
Lights. Oh man. But I have to stop ranting now. You may get the picture by now. The game has allowed me to make it behave exactly how I'd like my perfect game to be. Which took me twelve years. So for me this game has no competitors.
One more thing that lifts MW to tremendous heights is MCP. I don't need better graphics in MW, or better bodies or ragdoll physics. I need uncapped skills and attributes, i need bigger map, and the tons of comfort that MCP offers.
So to me the original MW was a great game. By allowing me to tweak it to my heart's content, it made itself unique. Adding MCP to that highly volatile cocktail turns High Level Gameplay into a Nuclear Nirvana. Always the chance to die, even with 1800 Health. But that's what those potions and spells are for. And Items.
And Daggerfall and Oblivion too I consider sublime, each in its own way. I added some dynamite to Oblivion as well, but by no means as extreme as what I did for MW. YET. And DF is so delightfully new to me, and so compelling. Those huge dungeons took only a couple of weeks to become friends I love to visit again and again. Even when there's seven Vampire Ancients in one room...