That's totally fair, man. Morrowind was one of the first games I binge-played when I was younger, so there's a pretty deep association here. Since I'm a huge fan of all of the Elder Scrolls games (save ESO, but MMO's and I do not get along), I've definitely spent some time thinking about each game's positives and flaws.

Overall, my first pick goes to Morrowind. Though now a bit dated, I found it to be the most detailed and lovingly crafted world, filled with lore (oh the books), secrets, beautiful and individually made caves, ruins and interesting cities. This game also doesn't baby you. The journal system is good, and gives you accurate information, but the rest is up to you. Fast travel is in game. There's no enemy leveling system--If you get in over your head, you will get stomped. Morrowind is by far the most in-depth and detailed world of III, IV and V, has an intriguing story, people, factions.

It's hard to choose between Oblivion or Skyrim as second for me. I really do enjoy both quite a bit, but I think I'll go with Skyrim here. Oblivion slightly offended me in some ways. Let me go on a slight rant here. In Morrowind, there is ONE full set of Daedric armor. Which is the best heavy armor in the game. Of course. But it's the rarest and most difficult to craft armor in the known world. Needless to say, I spent a long time hiking around for each piece. Then Oblivion comes around, I hit level 20 and BAM! Every goddamn bandit has a full fucking suit of daedric armor, apparently the same which I stomped through a Dark Botherhood sanctuary to get. Anyway. It's got its flaws, but Oblivion is also great. The environment is beautiful, but cave and ruin exploration gets dull extremely quickly and the lore isn't as in depth.

Unfortunately, I haven't played Skyrim as much as I've wanted to. Computer problems have since put a halt to further explorations. That being said, I did beat the main storyline and a few of the guild storylines, but I hardly consider that as thorough as a TES game deserves. While not up to the same par of worldbuilding as Morrowind, the exploration aspects were improved from Oblivion slightly.

Edit: TL,DR: Morrowind is tits. Oblivion and Skyrim are not as great tits.