Don't use the tired notion that weed is better than alcohol. Yeah you can't overdose on weed I suppose, but that isn't really relevant. There have been damaging effects involving weed, all the addicts I know in my life have had a problem with weed, not alcohol. I even know a guy who got depressed on weed and committed suicide. The fact is, without control or moderation, they both can be very harmful. And if they are moderated, then they can both be very fun.
Of course the pros and cons of both would see weed win every time in that case.