GHB, for one, is said to be all the best parts of alcohol with less of the downsides. It's still addictive and super illegal though, has the stigma of being a "date-rape drug", is maybe more neurotoxic than ethanol (excitotoxicity may be more in play), but definitely less toxic for the rest of the organ systems, and non-carcinogenic.

Kava, a beverage made from the roots of the piper methysticum plant, is broadly similar to alcohol, but milder, more sedate, non-addictive, non-toxic, and legal almost everywhere in the world. It's expensive though (only grows in the tropics), tastes like dirt-water, and takes a bit of work to prepare.

English neuropharmacologist David Nutt has been reportedly working on a synthetic less-toxic alternative to alcohol for years, but it's unsure if anything will ever come of it.