Both image formats can produce excellent stamps; however simple images are always best in .eps and .wmf format to allow you to easily manipulate line thickness in the event the lines are too thin.
Part of the problem is the plethora of clipart available on the Internet today. If you do a search for restaurant food clipart, you'll get pages and pages of obscure images executed in a wide variety of styles. It's difficult, if not almost virtually impossible to assemble an effective brand building set from a variety of sources. The best solution is to find a clipart supplier that has pre-assembled sets executed by a single artist in a consistent style. One source, Toons4biz.com, has several clipart sets built around different types of food characters specifically designed for restaurant promotion. These cartoon characters include a chef hat, pizza slice, taco, beer mug, chili pepper, steak and others designed as a brand mascot much like the Jolly Green Giant or the Pillsbury Doughboy. Each comes in a clipart set with many versions of the character, and logo templates, so restaurant owners can build a robust marketing and brand building campaign around the character.
Publishing programs such as Microsoft Publisher. Many publishing programs contain a data base of artwork that can be used in any document