I use Exposure2 myself and its amazing and very accurate, with allot of choices in film as well as individual adjustments to the presets: including grains size and strength among many others.I can highly recommend Exposure2, and am very satisfied with it. It very accurately represents both the Ilford HP5 plus 400 and Delta 100 that I commonly use in 35mm, and apply it to all of my digital photos. I cant give a comment on the others but Exposure2 is wonderful.
here is a glimpse of Exposure2's layout and settings.
http://farm4.static.flickr.com/3052/2725151290_f3b5618b42_o.jpg<-for full res
Click on the image to view it in a larger size