Thirstystone sandstone coasters have worked best for me. They absorb moisture, don't stick to the glass, and the cork backing keeps them from sliding. If you're looking for coasters for drinks that do their job, these are a solid choice. They also look good on a table. Cork alone wears out too fast, silicone doesn't absorb, and leather looks nice but isn't always functional. A stone with cork backing is the sweet spot.