The main reason to pick GSB would be VC or a similar post-mba goal.
There are some substantial differences between the two programs - the teaching method at HBS being mostly case-based and Stanford a bit more traditional lecture approach. That's a big difference to me at least. Recruiting is also different at these schools - GSB has a smaller class and is on the west coast so not as many East Coast Fancy pants companies make it to the on-campus recruiting. However, I doubt you would have issues finding a job with either one. I would caution you about the size of the network though - it is not the size but the quality that matters here. I could argue that Tuck's and Stanford's networks are probably stronger than HBS's due to the size of the programs. Smaller is usually stronger and more likely to yield success in connecting with an alum.
I think HBS still wins in many/most cases. In terms of GSB advantages, they are somewhat superficial - weather would be one; lifestyle and CA vibe - more relaxed; if you were planning to stay on West coast, that would be one more reason.
Congratulations!