This is just about questing in general, feel free to read it at your liesure.
Spoiler Note: these are all opinions, feel free to disagree
Questing plot experience: Morrowind > Oblivion > Skyrim
Oblivion's fighter's/Mage's guild was much more entertaining at the time at least than Skyrim's Companions/College of Winterhold. Morrowind overall was much more creative in the way quests unrolled, and how they were set up. Naked barbarian who got paralyzed by a witch anyone? Nord in mournhold saying "No, some witch didn't steal my clothes, it's too damn hot here". I never even gave that barbarian a cure paralysis potion.. I feel guilty.
Main Quest experience: Morrowind > Oblivion > Skyrim
I think this one is pretty self explanatory. Alduin was a joke, being the "hero" was overplayed. Oblivion's was long and tedious, making you shut down a ton of Oblivion gates, at least with dragons you can get it over with quickly.. but overall the ending/plot was much better for Oblivion. Dis Morrowind's main quest, I dare you, I will defend like the fan boy I am.
Overall questing experience: Skyrim > Morrowind > Oblivion
Graphics + awesome combat made quests more enjoyable in Skyrim. Morrowind is just morrowind, can't say anything bad about it.. is this sounding really biased? Morrowind was rather tedious/long distances/confusing, but that was the beauty of it, and if you didn't have the patience, you could always find in-game ways to raise speeds to incredible amounts. Oblivion is just yuck.. maybe I just overplayed it, but something about questing in Oblivion was boring.
As for ESO, I think taking the Morrowind's approach of: "Don't know what you're doing for a quest? You get killed/screw up big." Take a wrong turn and you're lost, lost in the wonderful world of tamriel, not knowing what you're going to find. I don't want a quest marker telling me where to go like some extremely linear themepark game. At least make ESO feel like its open, and it should be explored, I don't care about exploring a compass.
They've already said that their dialogue would make you feel engaged, and that you'd actually need to listen to it. Hopefully its more-so than Skyrim/Oblivion, but I'm not holding my breath.
In Morrowind, no matter how many times I played the same quest over again, I found myself reading the dialogue. It needs to be entertaining. After hearing "Oh, back from bleak falls barrow.. you didn't die it seems" I find myself clicking him over and over again to get it over with. Text allows there to be a certain depth I don't often feel with voice acting. Text lets me progress at my own pace, dialogue makes me sit around and wait. Sure voice acting is a tad bit prettier on the surface, but text lasts longer for me. I can't say I won't enjoy voice acting, and we already know its in, so I won't complain, and nor am I necessarily expecting text everywhere, but if they did the same level of detail Morrowind did with quests... oh boy I'm in for a treat.