My sister gave me an audio book version of Curry reading A Christmas Carol. swoon
My instant reaction to the thread title was Melanie Griffith. Nails on a blackboard.
For best male speaking voice I would add Warren Miller (director/narrator of ski movies) and Terry O’Reilly (radio show host). I would also add Candace Bergen to best female voices.
Oh… oh my. May have to look that one up to make it my own.
I have to add Garrison Keillor as one of the best. When I was in college and couldn’t sleep, I would put on ‘Stories from Lake Woebegone’ and his deep, soothing voice just made all the tension in my body melt away.
Also Liam Neeson. I saw him recite the alphabet on Sesame Street once and I swear I almost…it was Sesame Street for crying out loud! Dear lord, I want him to do it again.
I love listening to Clancy Brown, especially in villain mode (Mr. Krabs doesn’t count). He has this luscious purr that’s just…dreamy.
Seconding Matthew MacFadyen, very hushed and soothing. Speaking of soothing, I was recently introduced to UK comedian Stewart Lee, and his voice could lull me to sleep (meant in the best way possible).
Liam Neeson, too, regardless of what accent he’s using.
For women, PJ Harvey (speaking, and singing too), Gillian Anderson, Nigella Lawson (the rest of her ain’t so bad either), and…well, my mother. It’s too bad the rest of you have never heard her, because her speaking voice is really lovely. 
Edit: ^^^ Ha, good call on Liam Neeson!
I came in to say this.
That reminds me of another great voice: Patrick Stewart.
I was going to mention a secretary I used to work with. She had this amazing voice.
Any list that does not contain the late great Mark Lenard lacks logic. Here’s an audio interview from 1986.
Is it just that you (presumably) dis-agree with her politics? Because, taken in isolation, she has a very pleasant, well-spoken alto voice. For instance, I quite like Mike Huckabee’s voice, and find him pleasant to listen to, he seems like a very affable person…it’s only when I listen to the words he’s saying that I have a problem.
I agree that he has a wonderful speaking voice. His singing voice is, at best, regrettable.
I find his singing unlistenable.
My favorite female speaking voice is Shohreh Aghdashloo, though I could understand why some people might find her voice on the opposite end of the spectrum. The combination of accent and timbre just makes her someone I could listen to for days.
Worst: The late Howard Cosell, Jay Leno
Best: Sofía Vergara, Jodie Foster
Damn, runner pat; were you a hall monitor in high school by any chance? I envision you reading the Dope with a whistle between your lips. 
mmm
No love for George Takei? I could listen to him reading the phone book.
I find Cosell’s voice inherently funny and good-natured, not to mention resonant and sonorous albeit the nasality and borderline grating Dead End accent.
Joaquim de Almeida. I’ve heard him narrate a couple of short animated films, and he’s fantastic.
So strictly following the OP, you want me to produce 60 names? That would be mundane and pointless.
Instead, I’ll say H. Jon Benjamin but I won’t specify my catergory.
He was mentioned in the OP.
Mike Rowe, the host of Dirty Jobs, has a great speaking voice.
Vanna White, the Wheel of Fortune letter-turner, has a dreadful speaking voice.
I’ve always thought the qualities of a person’s speaking voice was underrated in the entertainment field, at least by the average person. Everyone talks about looks, but many of those good-looking actors also have a great voice. Folks might not always think about it consciously, but it colors your perception anyway.
Like I said, you don’t have to strictly follow my suggestions. :rolleyes:
But if someone does so—especially if they did it in a certain order—that would have been excellent.