Ooh interesting topic
How about the voice from the bitmap brothers Chaos Engine? I don't know how it sounded on the PC but it sounded great on my Amiga 1200.
https://www.youtube.com/watch?v=GqP2EnsQGqM
If you go to 8:42 of this video you can hear how clear it sounded!
He would also read out the power ups you collected:
Food
Special Power
Special Activated
Node Activated
Exit Open
Level Complete
World Complete
Ahh! (He said that when you got the gun upgrade, very strange)
Players Save
I can't remember many more voices from back then, I had a game called silly putty where when you died a voice said "Too bad!" but it wasn't all that remarkable.