To answer your question, yes, like anything there are huge differences in door quality. They will most all fill the gap, but features vary widely: insulation, seals, fit, finish, wood, metal, (gauge), windows, track thickness, roller/hardware quality, warranty,etc. I've been looking for two years and still haven't found the perfect door for me yet. I'm gonna go with the closest thing I can find to it very soon as winter is coming. Haas makes a pretty nice door from what I've seen - many different models/options so look closely.