All the 'serious' A-Levels take time and effort, I think! However I did General Studies and Critical Thinking at AS and they were both pretty simple, which is probably why very few universities accept them.
With General Studies, we had about three hour long lessons at the beginning of the year and that's pretty much it. I didn't revise because I didn't care about it (don't really see the point of doing it because no one takes it seriously!) and I got an A.
I did Critical Thinking AS in year 11 with one hour a week and very little homework (like a few questions every other week which most people didn't even do), didn't revise before the exam and got an A. I then took it to A2 in year 12, still only 1 hour a week, slightly more homework but still nowhere near any of my other subjects, revised a little for the exam, got an A.
They're stupid subjects in my opinion because they're 95% common sense more than anything else, but if you're looking for an easy subject to do then go for one of these! Just remember that if you're planning on applying to university, they will most likely not be accepted as part of your offer.