I can only generate 13-14mph ball speed due to my small body with 250-300rpm, hence I tend to match up well with high RG+mild coverstocks.
For extremely slow ball speed bowlers like me, I need a straighter angle, and all the rotational energy I can get at the pins to carry more.
Karma green was pretty good as well but doesnt seem to preserve the revs as well.
Karma pink was stronger cover hence I had to drill it weaker.