Andy--In my opinion the Spare Storm is the straightest. Besides the Storm,
I own a Big Blue spare ball, a Visionary Infra-red Amulet, Target Zone, Black Knight, Clear Wolf, XXXL, and Blue Dot. They all work fine, but the Storm is a bit straighter. Until about 1995 the Columbia Blue Dot was the straightest,
imho, but due to brittleness problems Columbia used the same formula polyester resin for the Blue Dot that was (is) used for the White Dot.