Best Glue for Ceramic to Ceramic
PVA glues are the best for bonding porous surfaces such as broken ceramic edges and unglazed pottery. Superglues will also work but have a much faster setting time. Both dry clear and form a medium-strength bond that will hold up for normal household use. Only a thin layer of glue is required so these glues are ideal for when you have pieces that fit tightly together.
These FDA approved food-safe adhesives are designed to come in contact with food. Both of these recommended products are silicone-based which means they are waterproof, flexible, and work across a wide temperature range.
When gluing a non-porous ceramic surface, you'll need something stronger like an epoxy. Epoxies are a little harder to work with but will create a strong, permanent bond.
Epoxies can also serve as a filler material for mending ceramics that have gaps. Epoxy comes in different colors and can also be sanded and painted. If mending a larger gap, consider using an epoxy putty instead.
In a pinch, you can also use this baking soda trick to turn a superglue into a gap-filling paste.