The two big problems (Not counting the fact that the TES team doesn't actually patch it) with Oblivion is that it was made for the console-tards, and it
needs to be modded because it was
never finished.
http://www.tesnexus.com/I recommend:
Oscuro's Oblivion Overhaul.
wpz_inv - Dark UI version.
Dark UI.
Expanded Hotkeys & Spell Delete.
There are more, but I'm not listed all of the mods I use.
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As for Morrowind.... It has a better storyline, better dialogue, more usable land, non-nerfed leveled lists, and thousands upon thousands of good mods. But it isn't as fast-paced as Oblivion.
I'd recommend searching for videos of the gameplay before deciding.
If you do get it, download Vibrant Morrowind.