The vast vast majority of interesting technical work is done in large organizations, or at least organizations that have enough people that you're not "picking your clients". Small companies that have genuinely interesting work are sadly the exception rather than the rule. Many of those small organizations support themselves with DARPA R&D contracts or the like. If you really care about interesting work and colleague…
Small companies have a lot of work. A lot of work doesn't actually mean good work. Unless you are simply looking to undergo a form of endurance training.
I agree, it seems that smaller companies as for more work for less. Usually, in my experience, they need something to outfast, but don't care if its made correctly since they just need to look good to sell the business.