Depends on what tea I'm drinking. If it's some premium greenage I use my thick white porcelain Japanese cups. Shows off the color better. I also use these when I have guests drinking tea.
For oolong and puerh I use a 120 ml thin porcelain gaiwan that I broke the lid for. Makes a great cup and saucer.
For everyday sencha I have a green glazed bowl style cup I use if admiring the color isn't so much a factor. It is my prefered cup for drinking sencha.
And for matcha I use my chawan of course.
I may use 2 or 3 if I have the day off, otherwise usually just one or two.
YM 2010 this morning in my white cup.
Twinnings el-cheapo garbage in a syrofoam cup right now, as I got mandatory overtime and am just chugging copious amounts of this crap iced to stay awake.