What bugged me the most in Oblivion about voices wasn't that there were like 8 of them (though that did kill it for me) but the fact that Elves sounded like any other humans, and the beast races (Argoinians and Khajiit) just sounded unnatural, I prefered their voices from morrowind (even though they weren't used much). In morrowind High elves always sounded and talked like they were high and mighty, Dunmer had that unique accent, and Wood elves, well, I always knew when a wood elf was nearby just by the sound of their voice.
Also, just my personal rant on the models for beast races. Quite honestly, I hated them in Oblivion, I mean they are BEAST races. They don't have to be almost alien looking like they were in Morowind, but acknowledge that they are not humans, and they should not look and walk like humans with furry faces and pointy ears or horns.