Like others have said, text prepared with the computer is easier to edit, share with multiple people and search. So, if the document I'm producing has those characteristics, I type it. If not, I tend to hand write it.
I learned to touch-type on a computer about 35 years ago (one of the most useful skills I ever acquired). Even when I choose to type, unless it is something very short, I mind-map the topic with pen and paper before typing onto a computer or writing by hand. I find the computer engenders a linear mode of thought (rather like writing ideas out as a list on paper) and therefore inhibits the free flow of ideas. Mind-maps seem to allow me to get all my thoughts down and worry about structure later. I've tried mind-mapping apps but they don't work work as well as pen and paper does for me.
When typing I use special text only editors for the first draft so that I can focus on the quality of the text without being distracted by format. I format the document only after I'm satisfied with the words.
Although this process of paper before keyboard sounds slow, it is actually faster in the long run. Using pen and paper first means that the thoughts I wish to express are more complete and logically organised before I touch a keyboard. I therefore require fewer drafts. It also tends to result in fewer torn up pieces of paper when trying to write letters.
On a day to day basis I use both paper and electronic journals. The former is easier to use in meetings or on the phone, the latter are easier to search and carry around.