You typically will have a far more varied job description than in a company of 25,000. You have a great chance to make an impact in a company of 100 people. Your opinion will reach the President and you may well personally know each other on a first name basis. In a large company you may only read about your CEO in the newspaper. You participate in more decisions rather than carry out decisions that may have been set in a different State or even a different country by people you have never met.
Risk abounds everywhere, as does opportunity.
Some small company CEOs can be tyrants and some large companies can be very accommodating. You will learn from all of them. I have been lucky to have a wide range of experiences. I've consulted for a dozen others. I started one company in my garage and advised others on doing the same.