Interesting. The thing with my previous job is that it was very much a consulting job too, with which consulting was used to bootstrap its own products. It didn't have that 'Silicon Valley' feel (is there even such a notion?). It wasn't funded. Extremely laid back. Non-existent teamwork (you're pretty much left to your own devices). 80% of what I learned, I learned on my own. No mentors to look up to. Still I learned enough in that it led me to these job offers (and tons of interviews), but it left gaping holes in my knowledge-base that most other startups want (I'm quickly remedying that though).
Company 1's environment looks to be the standard Silicon Valley startup I always envisioned it to be, but still it's too early to tell if it will or won't end up being a dud.
Still, you have some valid points. I will certainly take them into account when making my decision. Thanks.