How can I seal between a concrete patio and a brick wall?
Urethane or silicone caulk are the usual, but there are others that remain flexible. Read some labels at your hardware store. Flexibility is crucial, so don't use latex. If you have a lot of seasonal movement (frost heave), caulk might not be a good idea anyway.
Either match color or go with clear. Use as small a bead as possible and avoid smearing it out onto either surface by cutting a fine, angled point on the tube and pressing firmly.