Alcohol, no question.
Thing is, I think people are misinterpreting legal high. LSA is a scheduled substance. Most RCs are technically illegal for human consumption, except for MDPV (not an analog of anything), 2-dpmp, and the cannabinoids. DMT in any herbal form is still illegal, so is mescaline and 5-MeO-DMT.
All this only applies to the US, of course. Cannabis is legal in Breckenridge, Colorado, and I've smoked it there. Not totally sure if that counts.