I had the realization today in a meeting that I work for the biggest company I've seen in about eight years. I was in a meeting where I didn't recognize most of the people. Technically SeaWorld Entertainment was bigger, but I was a contractor and IT/software isn't the business, so it's not a good comparison. I had a recent Facebook memory that reminded me of another job for a very small company, and what a difference in situation that was.
There are a lot of exciting things that come with a small company, not the least of which is that the scope of your impact is generally pretty huge. If you work with 10 people or less, what you do has very apparent daily consequence. You might be trying to validate a business or find product-market fit. If you get lucky, you might even be able to grow it into something that involves a big pay day.
Unfortunately there are a lot of negatives to this as well. Sometimes the small business is an experiment that will end in failure. There's nowhere to go in terms of promotion and pay raises. You may work with owners or founders who are megalomaniacs, or more likely, good idea people who are terrible at operating a business. Sometimes the business just loses focus and bets big on a side endeavor that tanks the company. In the software business, there's just a lot more risk.
Big companies can be a great place to work, often for the contrasting reasons that you would expect. There is often a great deal of flexibility to explore and do what you're interested in, and promotions are a thing. You can even change disciplines completely, in some cases (I did this at Microsoft). You're rarely the smartest person in the room, and surrounded by people you can learn from. There's some amount of safety and stability as well, and often better benefits.
The dark side of Gigantocorp is that it could be slow, dumb and bureaucratic. If it's poorly organized, you can be more number than person, and you don't have the opportunity to be impactful. I can be outright difficult to make things better and you don't know who to go to when you have something that could move everything forward. You're bound to processes that create little to no value.
Of course, these are all generalizations. I can't say that I inherently prefer one over the other, and it's interesting how the experiences in both inform working in both. Right now I'm in the "big and growing but not giant" category, which is exciting and new territory for me. I mercifully only had to hire two people this year (what are the odds they both came from PA?), so mostly I'm rolling in an establishment instead of building everything from scratch.