Depends heavily on the experience I am going for. If I feel calm enough to get immersed, I will bust out a big game. But often times, when I get off work, I just want to play some Shellshock Live 2, and simply unwind by shooting tanks all night.
There was a point in time, when I thought that flash games were the best. I was broke, and didn't even have a hard drive in my computer, so flash games were about all I could do. They were "purer" games to me. They built around a mechanic and ran with it. But, flash games these days are rehashes of other games, and unique games are harder, and harder to find. Huh. Sounds about right.