The answer to this question all depends upon what type of surface you have to work with. For the most part, the suction cup can be pretty reliable. Where it often fails, however, is in the quality of the surface being used. If your countertop is a little dirty or has a thin layer of oils on it, or even if it is a little porous- you might run into trouble getting it to stick. Users sometimes skip the countertop and simply suction it to a cookie sheet or something that will work better with suction. The clamp option is a little less fussy and easier to ensure that it is securely in place, but it isn’t without its flaws. The mouth of these options is typically a little narrow, which means that the lip of your countertop cannot be very thick. Plus, due to its design, it means that it will only be able to be mounted on the end of tables and countertops, limited places where you can place it.