I've never had it, but I'm interested in all the Vanuatu Kava Store (NK, GKE) stuff.
According to the CoA's they post on their website, Kaolik had 7% overall kavalactones, while Marang only has 2.6%.
Which makes Kaolik look like the most cost effective, to me. Their stuff seems to be noble, but some of them might fall into the 'medicinal' kava territory, which I personally like for it's muscle melting qualities.
All their products seem to be on the low-med side of overall kavalactone percentages.