There are so many crappy biographies … would you rather read a poorly-written biography of a fascinating life, OR an exquisitely well-written, wonderful read of one of a not-so-interesting life?
What, no Harry Potter question on its last day as an active fandom? Huh!
I think this is pretty cut and dried—the latter, of course. Fantastic writing can make that supposedly uninteresting life interesting. Poor writing can make the most interesting of lives boring, especially if it handles them poorly or insensitively.
The Literary Omnivore 
Great answer! Why waste time on poor writing, whatever the genre or subject?
We have very similar answers: http://abookishaffair.blogspot.com/2011/07/booking-through-thursday-9-biographies.html
Good answer
here’s mine:
http://tributebooksmama.blogspot.com/2011/07/booking-through-thursday_14.html
I usually prefer a poorly written biography of an interesting life.
How concisely and well said! Poor writing can destroy even the best subject sometimes.
I’d rather it be interesting, even though I don’t like poor writing.
Here’s My BTT
I usually prefer autobiographies. Something about a story told in the writer’s own words, I guess. Some of my favorites are Agatha Christie, Issac Asimov, and oddly enough, Steve Martin.