Cost wise I definatley prefer the loam. I also like the driing style. I love the preciseness (if that's a word) of the blue groove and how you have to be in the line.
A really nice mix would be Competition Hobbies in Tucson, Arizon. Red Clay that's watered. Slicks work the best from my experience there. Even Holeshot's didn't work as well. And the slick should last a long time.