Standard: I used to play with mouse and Z/X, but now I play with tablet and Z/X
I sometimes play mouse-only, usually to not make so much noise (I click the buttons on the keyboard a little too hard so it makes a lot of noise)
And when I can't use my tablet I play with either mouse and Z/X or mouse-only.
I prefer tablet and Z/X (or any other buttons on the keyboard of course)
Taiko: ASDF or ZXCV
CTB: I rarely play CTB, I use standard (left and right + shift)
Osu!droid: index finger on right-hand, one-finger tapping even in streams (I've beaten mad machine [champion] too)