If you are looking for affordability then you might lean more toward the glass tip pH meter. The glass tip on a pH meter is very easy to break. pH meters are one piece of equipment that most gardening stores hate to carry because of how easy it is to break. If you are looking for reliability then you might lean more toward a silicone tip pH meter. If the tip of either the silicone tip or glass tip meter dries out then the meter will not work properly if at all.