As stated in the other comments, there's really not enough information. I would lean towards #2 because of what Mark Suster calls, learn before you earn.

#1 you're going to have to figure out a lot of things on your own. Now that's not a bad thing, but the experience may come quicker if you have some more senior people to watch and learn from.

#3 sounds like a consulting company so the things you learn will be around how to run a consulting company

Now of course the big assumptions I have made are:

You interested in product oriented startups vs consulting

You are pretty confident in your ability to pick up technology. You are more interested in learning the process, etc

You're not in it for the money but the chance for eventual glory

If any of these assumptions are wrong then the answer of course changes