Now that that's out of the way, I'll get on with it.
I have worked a very small company, medium-sized companies, and a couple really, really, big companies. So far, in my experience, the medium companies seems to have the better balance. The large ones seem to be riddled with excessive politics, backstabbing, and game-playing, and the small ones, imho, are usually not that stable.
The one small company where I worked laid me off after three months because they were going under. Therefore, the only comment I can make about my brief time at a really small company is that I decided to look for a very large company that would stay in business for a long while. So....
At my next job (a very large company), I saw good managers marginalized by the incompetent, and the highest-quality workers laid off time and time again (myself included). 'Twas once a decent place to work, when I first started there, but since then, it had steadily declined. The visionaries at the top were ousted by the "management school fad following" fuddy-duddies. From there, successive layers of management from the top down were "adjusted," until the whole chain was only following the latest fads. The latest example of this before I left was Six-Sigma. The end result of this "business process streamlining" was massive downsizing, and the replacement of full-timers with overpaid (and usually not very good) contractors. I don't blame this on the contractors themselves; in fact I've even become friends with several of them. Another part of this management strategy was to promise employees things and not deliver. Also, directors - technical, not board - were actively encouraging the lower-level employees to report on other employee's doings. As time went on, the stress levels increased dramatically. Morale all around was at an all-time low. I guess this is what the politicians mean when they refer to the "trickle-down effect." Finally, just as I started looking for something else, they laid me off. What a relief!
Contrast this with where I now work. Mid-sized company where the executives were also the founders of the company. They all take pride in their products and services they provide to customers. And yes, the executives refer to them as customers, not consumers. This philosophy runs through the entire management structure. They actually treat the employees like the people we are, rather than just resources. This makes all the difference in the world. I find it very motivating and refreshing! For the first time in several years, I actually look forward to going to work again.
If the time comes that I decide to look for another job, I will have a difficult time making a decision if I receive any offers from large corporations. Or not.