I write my best in scenarios that I could see happening, given a moderate suspension of disbelief.
The first two stories I joined are ones that are based in some sort of Medieval/Victorian setting. I've always loved to read that sort of literature (both fiction and nonfiction) from those settings. They're the most "real-life" ones that I'm doing, except for a new story about a mob boss and the little sister of a rival who naively wanders into the club he owns. That's the most real life one, since it's set in present day New York; however, I still find it easier to write in the old-fashioned ones. The Asylum extreme small game that I run isn't very realistic, since no psychological facility could be run that way for long without severe penalties/consequences. I still prefer for all patients to have a legitimate explanation of their psychiatric disorder(s) though.
Like you, espina, I think that RL is easier to write for, but that's precisely why I don't like writing for it all that much. I enjoy the challenge that writing for a fictional scenario presents. I do my best writing that way, and I also like reading it a lot more than normal, modern situations.