FT out of school at Large established tech co or startup

I've been studying startups for the past 4 years at university and find tech/growing companies to be the most interesting fulfilling thing to do in a career. During the summer of 2018, I interned at a VC in Columbus and thought one of the startups in the portfolio was a very strong company, but wasn't really excited by any others. After interviewing all through my senior year, I ended up committing to a Sales role at Salesforce. I chose sales because I'm generally a competitive and outgoing person, knew this was a skillset heavily desired by young/growing companies, and that there is more of a meritocracy involved than more project based companies. I got the job in May, but because it's in a cohort and due to location I chose, I didn't have to start until Nov. So in the meantime I reached out to some contacts (I'm very familiar w/ C-Suite at the startup mentioned above, and even interviewed there earlier but was ousted by internal hire) and started an "internship" at company in Cbus to earn some money and do something productive before starting at Chicago. Basically, the internal hire who took my job is stepping down, and they asked me if I wanted to consider full time (w/ equity). The company is in a hot space (Enterprise Collaboration) and has been talking to all the big players (FB/Slack/Microsoft) about Series B/potential acquisition and has been closing customers like crazy this year. I now have to let them know by Monday what I am thinking. On the one hand, I chose SF because it's the fastest growing software company to 10bn ever, and must be filled w/ good salesman and is a reputable name that will allow for other opps. On the other hand, my long term goal is to found/be a founding member of a startup and here that lies in my hand with potential for payout. While the startup is clearly a good option, I don't really want to live in Cbus and there is definitely no rush to accomplish the goal above, especially with how little I feel I can contribute right now. I would love to hear some thoughts from those a little further along in their careers, because I'm from a small town in Ohio, my parents have no idea what I'm talking about, and was really excited to start this next chapter in my life. Now im unsure if that's the right call