Jane Burden (maiden name) was a big favorite among the PRBers, but I don't think it was because she was knockout, I think it was because her face was impassive.
http://web.ukonline.co.uk/wildbunch/images/jane.gif
http://www.css.edu/USERS/phagen/hon4777pr/janeburdenphotow.jpg
http://home.clara.net/reedhome/oxford/graphics/two/jane_burden_tn.jpg
http://www.victorianartinbritain.co.uk/muses/janemorris.jpg
http://www.libfl.ru/pre-raph/photographs/51.jpg
Besides, the original Pre-Raphaelite "stunner" was Rossetti's wife, Elizabeth Siddal.
From Wood, Christopher. The Pre-Raphaelites. Weidenfeld & Nicholson, 1981 (I own the 2000 paperback edition):
According to William Michael Rossetti, this picture (Millais' Ophelia) is the best likeness of Elizabeth Siddal ever painted.