Either would be fine, as to whether beige/ivory white or black, it boils down to your personal taste or aesthetics value (as long as it has the switch type you prefer). Personally, I like the beige one, pretty old skool looking....I was in the same position as you, got a black one as I couldn't find a beige one. Then when it turned up in the Used/garage section of a local tech forum, I grabbed it as well.....swapped their key caps around.
Show Image
(http://img.photobucket.com/albums/v333/mikeysg/20130818_150757_zps47f7a6c5.jpg)
thanks for the pic, explains much :)
i'm leaning towards the beige case too, i think it will look better with various colors of caps, such as the set i posted in the OP.
i'm no design expert or anything, just feel like it's a more neutral color. not 100% sure yet though.