Daggerfall was quite impressive for its time and a step in the right direction, even if it had too many flaws to be considered a great game. It was also ugly as sin, and catastrophically buggy.
Morrowind on the other hand is game that "fixed" what was good about Daggerfall, and kept the crap as a central gameplay feature. Oblivion, I'd say it's a slightly better Morrowind.
I dunno, Pidy. I kinda regard Oblivion as a simplified Morrowind. Morrowind places greater importance on class. The choice and level of major and minor skills determines the guilds you can join and the position you can progress to, whereas Oblivion doesn't give two hoots who you are, you can join any guild willy-nilly, irrespective of class (Knights of the Nine rectified this, I think, taking into account player infamy). In art design terms too, Oblivion aside, Cyrodiil's a generic fantasy land in comparison to Morrowind.