The most suggested form is the easiest to look at, loose prints in clear poly sleeves. Mounted and matted prints are generally a waste of money if presented to a gallery. Any gallery owner worth their money will know what the prints will look like when matted and many would rather not have the prints mounted for presentation. Always contact the galleries you are intending to show your work to prior to presentation to get their desired presentation method. Loose prints also allow the gallery to handel the prints freely for possible edit and arrangement.