Silicone sealants stay permanently elastic and resist UV and weather, which makes them the standard choice for glazing, weatherproofing and sanitary joints. Acetoxy-cure types smell of vinegar while curing and suit glass and non-porous surfaces, while neutral-cure types are low-odour and suit metals, stone and concrete.
Silicones can't be painted, so where the joint will be painted, use an acrylic or hybrid polymer.