It's a tough choice. I would go to Stanford over Harvard personally, but thats because Im from CA, had more CA-oriented goals coming into law school and went to a small private college so the smaller classes appealed to me (although Im at a school now with a larger class size than S and happy with my choice). Harvard makes more sense for a lot of people, and it accounts in part for Stanfords' surprisingly low yield (people chose H over S in larger numbers than I would expect).
Don't buy the "SLS is all chill" crap, people still work incredibly hard and stress out there - law school is universally intense - although comparitively, my friends at S have a somewhat happier experience than Harvard, but this is anecdotal.
I think "fit" and "experience, after $, should play a large role here. Definitely visit for ASW and get the true opinions of students in the areas of practice/agency work you're interested, not just adcoms and the students who volunteered to white lie for the school on its behalf.
Sometimes these kinds of comments take flak on TLS, but I suggest especially with this choice that you consider the alumni network overlap from UG as well, if only as a tertiary consideration. People don't entirely stop caring where you went to undergrad, especially biglaw hiring partners and gov positions. If you want to be in California, Stanford is the obvious dominating presence. But consider the combination of networks (for example, If you went to Stanford or Berkeley for UG, Id go to Harvard to broaden your reach, whereas if I went to an Ivy undergrad, Stanford would do most to stretch your ties and connections). I've already found my undergrad/law school network diversity to prove valuable.