I really like the Comet warm white frosted bullet ones (8mm) or the retros and then strategic placement of color ones in the backglass or certain inserts.
There are some really great example pictures and references on the site:
http://www.cometpinball.com/category-s/1825.htm
To really make the backglass colors pop I like natural white, but I think it makes the playfield look wrong, it loses a bit of the EM feel.