I voted for all 3.
Lets me experience a variety. The spice of life.
And for those who don't know, if a survey has square boxes, you can select as many as you like. If there are radial buttons, you can only choose 1.
Yeah, this.
It all depends how I'm feeling, and I'd better have all the options! Also, there's a wide variety of terrain, baggage, frame flex, and (on tandems at least) stoker preference/strength/weight. Somewhere in there, among the many options, I can find gearing nirvana, but it lies in a different place each time depending on all the other factors.