Fully or mostly legal, in order: Kava, phenibut, alcohol, DXM, nitrous. (DXM did produce the most intense and most worthwhile hallucinogenic experience ever for me, but I prefer other dissociatives and would not do DXM again these days.)
Grey market, in order: 6-APB, methylone, 4-ACO-DMT, 5-MEO-DIPT. (Some are illegal now, of course, but were "legal" when obtained.) (Synthetic cannabinoids were kind of ok, but not nearly as good as the real thing, so why bother?)