Preferring person A to B seems the better choice only if its rather unlikely that person A is significantly smarter than you.

Assume you know the truth, and know or strongly suspect that person A knows the truth but is concealing it.

OK. You are on the rocket team in Nazi Germany. You know Nazi Germany is going down in flames. Ostensibly, all good Nazis intend win heroically. You strongly suspect that Dr Wernher von Braun is not, however, a good Nazi. You know he is a lot smarter than you, and you strongly suspect he is issuing lots of complicated lies because of lots of complicated plots. Who then should you stick with?