Who makes a good E-core coil?

Here is test method.
https://www.google.com/url?sa=t&source=web&rct=j&url=http://dkgsite.com/index_files/spark%20testing%20article%20062508.pdf&ved=0ahUKEwjXjOPTpoLUAhWq6oMKHWv6AfkQFggcMAA&usg=AFQjCNG72YJQbXPDnSK6YR1yw7YUwB5_rw&sig2=7fKICL1aezkix6HbdV2taw

An easy method is weigh them, heavy wins. :)

Much has to do with ignition primary peak current, peak primary voltage, plug type an gap, plug wires, and desired max RPM.