"Personally" => I think that a white background rocks!! => CNG seems to shoot the best coin-photos (you would be very wise to discover their caramel secret!!) ... sorry, but black just seems soooo 70's Brady Bunch Wow, I betcha that comment will attract a few flies, eh?
I think a white background is the most versatile and practical. I simply prefer the aesthetics of a black background for my own records and website
I use a simple Sony digital camera and I like cloudy days best, they seem to give the best color saturation. Sometimes, as with the Buffalo gold, P hotoshop helps.
I tried a few more. I also tried Doug's "black hole" method but it didn't work- my camera automatically adjusts the light so it looks really bright and I cannot shut that feature off. I'm OK with these though. Tetras of the Sileraians. Onkia of Panormos.
Any feature you can not control, adjust or turn off is what I consider reason to buy a different camera. There are a thousand different camera models and brands. They have almost as many feature sets. Manual white balance and manual exposure with manual control of aperture and shutter speed are features worth having. If for no other reason, going manual allows you to shoot both sides of a coin the same way.
I would be happy to photograph the Molinari collection of coins for the low, low price of one as (of my choice, of course). I feel that is a very Liberal offer. http://www.forumancientcoins.com/gallery/displayimage.php?pos=-95173
The only reason I was able to buy that coin was because I bought an ounce of gold for $600 when I finished grad school back in like '07. Gold was at $1600 in 2014 and when the As appeared I asked CNG if I could pay them half right away and half in a few weeks. I then sold the gold proof buffalo for $1700 and convinced my wife that, since we had a baby coming and I wouldn't be buying as many coins (ha!) that I should treat myself to this one. So no, unfortunately I can't part with it, Doug.