Weed because it's the more natural, and the healthier choice. Alcohol is essentially a poison, but it requires large amounts of ethanol to kill someone. It will still deteriote your health over time (obviously), arguably a lot more faster and detrimental compared to weed consumption. Cannabis has also a lot of medicinal properties and can help people who are suffering from physical pain, insomnia, depression, etc. the CBD oil in weed, not to be confused with the chemical THC which is what gets you high, has shown to greatly help those with cancer, seizures, and so on. Although a lot of that data is anecdotal, there are a lot of claims and stories you can look up to see for yourself. Plus, weed just allows you to let go and relax (unless you decide to "fight" the high and not give in), which is what we all really need every now and then.
TL;DR: Weed is the better choice. It's less bad for you health wise and can help you relax and chill out.