What’s the best adhesive for sticking to brick?

The best for going onto any uneven surface would be the Heavy-Duty PS52 and PS51, this is a rubber based adhesive similar to the PS14. Its biggest benefit is the thicker layer of adhesive on the back of tape, this enables the adhesive to get a far better purchase on any uneven surface. The Heavy-Duty is also the best to use for outdoor applications as it is weather resistant. The hook to loop connection is very strong so it can be used for semi-permanent fixings and applications requiring a more secure fastening; as a rough guide, a 100mm x 50mm piece will hold up to 15kg (given ideal conditions).