It depends primarily on how long you’re staying. San Francisco has high transaction costs on both ends: closing costs going in, transfer tax and commission going out. If your horizon is two to three years or less, renting is often the more responsible financial choice. The math changes significantly once you’re planning to stay five years or more. At that point, long-term appreciation, the Prop 13 tax benefit, and equity growth tend to outpace the cost of renting by a meaningful margin.
The other variable is your life. If you’re likely to take a global job, start a family somewhere else, or make major lifestyle changes, a mortgage in San Francisco can become a constraint more than an asset. I help buyers work through an honest timeline and financial analysis so the decision reflects their actual situation. You can read more about this on the blog.